Learning About Gardening Can Be Confusing With All The New Gardening Words And Names To Remember. So I Asked Gardeners The Following Questions About Gardening Terminology and Wrote a Gardening Dictionary to Help Them Master The Words And Enjoy Their Gardening. It’s Not Made Easier By the Fact Some Of These Words Are Historical And Some Very New.
Which gardening terms confuse you?
What gardening terms are new to you?
What gardening terms do you want explaining?
This dictionary is a work in progress, I’m starting at the beginning with A .. and slowly working through the alphabet. It’ll take time so please bear with me and come back as I write each new instalment!
Gardening Terminology – A
A layer of cells at the base of the petiole (leaf stem) where the leaf breaks away in autumn. Technically there are two layers of cells, in autumn the bottom one expands and breaks away from the top layer. It is believed that reduced sunlight and daylight hours leads to a reduction in photosynthesis and hence a reduction in chlorophyll production which then prompts abscission. in autumn.
Soil can be acid, neutral or alkaline and is measured on a pH scale of 0-14 with 7 being neutral. Acid soils are technically in the pH 0-7 range. However the most acid soils rarely exceed pH3 and few plants can survive very acid conditions.
The plants that enjoy, and in some cases require acid soils include blueberries, heathers, rhododendrons, azaleas etc. For example, most rhododendron species prefer a pH of 4.5-6. Naturally-occurring acid soils are found in bogs (hence peat is acidic), moorlands and coniferous forests.
Ericaceous composts are acid and used to grow acid-loving plants.
A measure of land totalling 43560 square feet (UK measurements). If its square that’s about 209 feet on each side. There are 2.471 acres in a hectare. Land in the UK is still sold in acres.
To confuse matters even further, historically an acre was a furlong by a chain. Roughly speaking this is the size of a football pitch (which can be anything between 100-130 yards long and 50-100 yards wide .. even square according to the rules!).
Said to increases a soil’s ability to prevent nutrient leaching and having benefits to soil microorganisms. Research is still underway in universities and at Wisely and is yet to confirm these claims.
Aerating consists of loosening the soil surface to encourage water and air penetration. It can be done by hoeing and other cultivation practices and is useful to prevent evaporation during hot weather.
Aerobe / Aerobic
An aerobe is an organism that requires oxygen. It requires aerobic conditions. See also Anaerobe.
Air is often forgotten as essential for plant growth. In most plants, air is taken in via the roots and soil or compost needs to be air permeable to allow for gaseous exchange at root level.
Hot air rises and cold air descends. Air drainage is when cold air flows down a slope. In cold weather this can lead to frost pockets ate the bottom of the slope, where the cold air lays in low spots.
See Air Propagation
A form of plant propagation where the cutting is allowed to root into a growing substrate whilst still attached to the parent plant. Some form of damage to the bark, where rooting is required, induces quicker rooting. To prevent that substrate from drying out the stem and substrate is normally wrapped in plastic to retain moisture.
The opposite end of the pH scale to acid soils .. see above.
Plants and some other organisms often exude chemicals that have a positive or detrimental effect on other plants. This gives them a competitive edge in the survival game.
For example, rice has allelopathic properties which seem to be inherited. And work is being conducted on breeding rice where it will inhibit competing weeds.
Black walnuts (Juglans nigra) produces an allelochemical, juglone, which inhibits many species and should therefore never be used as bark or as a composted material.
The onion family. There are hundreds of species within this family which includes onions, spring onions, garlic, shallots, etc
A plant leaf structure where the leaves appear alternately along the stem as opposed to opposite or in some other structured way
Alternate bearing refers to the tendency of many fruit and nut species to grow large crops every other year with much smaller, or no crop, in the in-between years. It’s like Bienniel Cropping.
Anaerobe / Anaerobic
Organisms that can, prefer or must live without oxygen are called anaerobes and live in anaerobic conditions. For example, Clostridium tetani causes tetanus and thrive in oxygen-depleted deep wounds.
Many, though not all, soil fungi are anaerobes.
A plant that lives for up to a year. They can go from seed to mature seeding plant in no more than a year. Some weeds can actually achieve this in six weeks … it’s why they are so successful at being weeds!
The part of the flower that produces the pollen. It is on the upper part of the stamen.
A plant pigment that provides blue, black purple or red colouration depending on the pH.
A fungal disease affecting leaves and fruit
A small sucking insect that sucks the sap from plants. Aphid are parthenogenic and hence capable of virgin birth. Most adults don’t have wings but every so often a winged generation occurs and they fly to infest new plants. Aphid are unusual in the insect kingdom in that they give birth to live young and are not normally egg-laying. There are huge numbers of aphid species and they range n colour from green to pink and even black (often call the black army when infesting broad beans).
A product or substance that kills aphids.
The botanical term that describes the process whereby the main stem of a plant is dominant over the branches and side shoots and where branches are dominant over sub-branches. The process is controlled by plant hormones, auxins, produced in the growing tip. Thus the dominant plant growth is upwards towards better light where photosynthesis is maximised. Should the leading shoot be destroyed or damaged a secondary shoot will become dominant due to the lower auxin level. It then produces auxins to become dominant in its own right.
Plants with a preference to grow in or near water.
A collection of trees and shrubs; often gathered together for scientific or educational purposes, or as in the case of some collectors to demonstrate wealth or intellectual prowess!
Normally arboreta are found in parks or private gardens. Examples in the UK include the National Arboretum at Westonbirt which belongs to Forestry England and Sidmouth arboretum which is unusual in not being a single site in single ownership. Sidmouth Arboretum is a collection of trees and shrubs spread across the whole of the Sid Valley, in the ownership of a number of private individuals and public bodies and organisations.
The cultivation of trees and shrubs as individuals and small groups as opposed to forestry which is the planting, growing and harvesting trees en masse for timber. Arboriculturists work with both ornamental and edible crop bearing trees such as apples, cherries, etc.
A tool designed to take soil samples from various depths OR a tool that makes holes to enable the planting of bulbs, plugs, or container/module or pot grown plants. Augers that fit in hand drills are particularly easy to use and can make planting much quicker. (Please follow the safety instructions provided with your auger).
The average date when the first and last frosts can be expected for a given locality.
The leaf axil is the joint between the leaf and stem on a plant. This area is where shoots often emerge. An example would be tomatoes where the shoot coming from the axil is the side shoot.
The bud produced in the leaf axil.
Gardening Terminology – B
A naturally occurring bacterial disease which, when used as a biological insecticide, affects caterpillars. It is also used as an endotoxin in GM crops to protect the crops against insect pest. Some subspecies of Bt are commonly used to control mosquitos and fungus gnats.
An American term that refers to how bare-root plants are sometimes sold with the roots wrapped in burlap. In the UK hessian or even plastic is often used.
Plants such as fruit canes are sometimes sold as bare-root plants rather than in pots. They will have little or no soil around the roots and will be protected from drying out by being wrapped in paper or an alternative cover.
Don’t think that if you’re offered a bundle of plants in a single pot they are necessarily pot-grown. They are often bare-root plants put in a pot to lengthen their shelf life. They weren’t grown as a clump of plants.
Bare root plants are best planted in the autumn when they are more likely to root and establish rather than in hot dry weather when they can dry out and die.
The bark of a tree or shrub is the hard outer layer that covers the roots, stems or trunk. Several other structures exist below the bark including cambium, phloem etc. The outer bark consists of dead tissue whilst the inner bark is living and includes the inner layers of the periderm.
Bark can be harvested for several purposes including as cork for the making of cork goods and as a bottle closure. Oak bark is used in the tanning process. Other barks produce spices, eg cinnamon bark, latex and poisons.
Bark is often visually attractive and many trees are grown for this reason. e.g Cornus species.
Bark is also used as a ground cover in pathways and on beds as a mulch.
The leaf that is formed at the base of the stem.
As in a blade of grass. Its the flattened green part of the leaf.
Blindness – Blind Bulb
Bulbs are said to be blind when they do not flower. bulb flowers are initiated in the previous season and blindness is often caused by poor growing conditions at that time. Drought, poor nutrition etc can all cause blindness.
These are plants that take two years to go from seed to seeding adult. Lots of veg are biennials, eg lettuce, leeks, carrots, beetroot, but we tend to eat them in year one so never see them flower. It’s a pity we don’t see them as some are magnificent, leeks, for example, can be six feet high when flowering and have a huge head of flowers.
The use of biological agents to reduce pests. E.g the parasitic Encarsia formosa wasp to control whitefly. Other examples include Bacillus thuringiensis to control caterpillars and nematodes to control slugs and snails.
A leaf structure where the leaf is compound with a paired leaf of feather-like leaves. Each pair is also divided into pairs.
When a plant bolts it means it’s going to seed. This is exactly what we want if we harvest the seed or fruit. But not so desirable if we want the root or foliage. Premature bolting is often caused by water stress .. ie underwatering or overwatering.
A phosphorus-rich fertiliser made from finely ground up animal bones. Phosphorus promotes strong root systems and is part of a normal general-purpose fertilizer.
Bonsai (the literal translation is tray planting) is the1000- year old Japanse art form where plants are dwarfed by growing in shallow trays. By restricting root growth, water and feed, along with careful pruning and training, trees can be miniaturised.
The Japanese created their bonsai tradition after copying the similar Chinese tradition known as Penzai.
In English, the term bonsai often means any form of miniature plant or even non-living miniature scene, in a tray or pot.
A fungicidal mix of copper sulphate and slaked lime often used in French vineyards, as a preventative regime, to control mildews and other fungal diseases in the late 19th century and thereafter. Used intensively for many years and the copper can become a pollutant!
The mix has also been used to control potato blight.
Despite the fact that both copper and slaked lime can be dangerous if incorrectly used and copper is a pollutant and is harmful to fish, earthworms, humans and livestock, it is approved in many countries for organic growing.
A trace mineral, important for flowering, fruiting and salt absorption. Boron is sometimes added to “boronated” fertilisers.
The two-part (binomial) naming system, devised by Linnaeus, used for plants and animals. Eg Digitalis purpurea, often shortened to D. purpurea. The first part of the name, the Genus, is always capitalised and the second part, the species, is not,
The scientific study of plants including their physiology, structure, ecology, genetics, classification and economic importance.
Botrytis cinerea is a fungus, often called grey mould or grey rot, that infects a wide range of fruit, veg and flowers. It tends to be more prevalent in wet or moist conditions and often infects plants that have been damaged in some way. Eg. tomatoes that split due to sudden increases in irrigation will frequently get botrytis. It is also very common on strawberries and grapes.
Botrytis is necrotrophic, ie it lives on dead plant material. In many cases infecting damaged plants and subsequently causing their death.
The practice where the bottom of a plant container is warmed to aid germination or growth. The heat supplied can be via an electric propagator, hotbed or other means.
The modified leaves, often sitting below the flower, that are often mistaken for the flower. Examples include bougainvillaea, poinsettias and some dogwoods (Cornus species).
A bract-like structure sometimes found between bract and flower.
The cabbage and mustard family. The genera include many species and cultivars. Eg Brussel sprouts, cauliflower, kale, turnip, kohlrabi, broccoli, calabrese, pak choi, swede, etc
No, not a media term! In this case, it means to broadcast seed, ie to spread seed widely by hand or with a machine. A hand-operated machine called a seed fiddle can be used to sow seed. I’ve used one myself to sow grass seed and it’s claimed that it can be used to sow wildflower seed. However, the problem with using it for mixed seed is that each seed has a different weight and therefore is broadcast a different distance. This means there is a tendency to get stripes in the field where the lighter seed hasn’t reached! The video shows a seed fiddle being used in Scotland, and the accent may need some careful listening if you are to understand it fully.
Buds are undeveloped or embryonic shoots and what leaves, flowers and subsequent seeds or fruit will develop from.
Where the scion and rootstock or recipient plant meet on a grafted plant. In most cases, it will be near the base of the plant but where grafts occur on stems or branches it will be much higher up. Grafted plants should never be planted with the graft below soil level or the scion may develop its own roots.
A bulb is an underground storage organ typical of the daffodil and lily families. It is effectively a self-contained bud, that can remain dormant when growing conditions aren’t good, that can be detached from the parent plant and will remain viable. It consists of a stem surrounded by fleshy scale leaves and flower. The embryonic flower is contained within the bud and will have formed between the time the plant last flowered and the time the bulb was finally formed. Blind bulbs have no flower embryo and are usually formed when the plant has been too dry after flowering or the foliage has been damaged before the bulb has been fully formed.
The practice of growing plants that attract and feed butterflies.
Gardening Terminology – C
A mineral used in the cell walls of plants. Without it, plants can suffer calcium deficiency that is seen as, for example, blossom end rot in tomatoes.
The thin layer of cells between the bark and stem of a plant.
The stem of fruit canes such as blackberries, raspberries, loganberries, tayberries, etc .. not forgetting bamboo canes and sugar cane. Generally speaking, canes are slender hollow plant stems.
A lesion on a plant caused by the breakdown of tissues due to bacterial, fungal and other agents. Usually species-specific and commonly found on the bark of some fruit trees, it can be of economic importance as it reduces yield and can kill some plants.
Capping is a term to describe cultivated soils that have a hard or crusty surface. this is often formed by the impact of heavy rain or water droplet from irrigation that has broken down the soil structure. Capped soils prevent the movement of air into the soil and lead to growth limitations.
Essential in plants for photosynthesis carotene is also responsible for the orange colouration in carrots and some yellows in dried foliage.
Any slender cylindrical cluster of flowers but most notably applied to hazel catkins or “lambs tails”.
Chalky soils are largely calcium carbonate based and hence lime rich. They are very alkaline eg. pH of 7.1-8.0, they will often froth if mixed with a mild acid such as vinegar. Where this occurs it demonstrates the presence of free calcium carbonate.
Chalky soils are highly visible. They appear to be white, or at least have small pieces of chalk in them.
Chalky soils are often shallow and overlie clay. The chalk itself will be free draining but the underlying clay will be wet and cold. This makes it a difficult soil to cultivate and grow crops in. Organic matter such us composts can be added to improve fertility but it decomposes quite rapidly.
Poor growth and chlorosis are common on chalky soils. This is due to plants not being able to absorb sufficient iron and manganese due to the alkaline conditions.
Plants respond to certain chemicals and are said to be exhibiting chemotropism. This can be seen within the soil when plants move toward nutrient-rich soils and in the flower when the pollen grain germinates and is attracted towards the ovary which releases chemical signals.
Some seeds require a chilling period before they become viable and can germinate. The chilling process is sometimes referred to as stratification.
The process where seed potatoes are placed in hitting trays in a bright, frost-free place so they can sprout before being planted.
Chlorophyll is the green pigmented material found in plants, algae etc that is essential to photosynthesis. It absorbs mainly blue light and to a lesser extent red light but reflects green parts of the spectrum, hence making plants appear green.
Chlorosis, and chlorotic growth, are characterised by yellowing of leaves due to the lack of chlorophyll. Although indicative of various adverse conditions such as poor light, pest and disease including viruses, poor nutrition, waterlogging, drought, low temperatures, incorrect pH or other cultural problems it is also natural in some cases. For example, young shoots are often chlorotic when they emerge from the seed, but green up quickly provided they get sufficient light.
Interveinal chlorosis is sometimes indicative of iron, manganese or magnesium deficiency. This isn’t necessarily indicative of low levels of these microelements in the soil or growing medium but is sometimes caused by the plant’s inability to mobilise them quickly enough. In the case of magnesium deficiency, this can be remedied bus foliar feed. For example, tomatoes sometimes run out of magnesium when at the 5-6 truss stage and can sometimes benefit from a foliar feed .. Epsom salts are the usual ingredient for this feed which is sprayed on the leaves in the early evening or other time when strong sunlight is absent.
A lack of nitrogen is also a possible cause of yellowing or reddening of leaves, especially older leaves. where the second indicator is a lack of plant vigour characterised by slow growth.
Leaves also go chlorotic in the autumn as the plant withdraws valuable nutrients from the leaves before shedding them.
A soil component measuring less than 0.002mm.
Clay soils are predominately composed of very fine granules and colloidal substances. The clay component of soil measures less than 0.002mm. Clay soils crack when dry and become very sticky when wet. This makes them a cold soil that is slow to warm up in spring and can bake hard in summer. The fact they can bake hard is why some clays are used to make bricks.
Clay soils are rich in nutrients and can range in colour from white or dull grey to orange or dark brown.
Most soils contain some clay and a small amount is beneficial. However, when it predominates it is a difficult soil to cultivate and grow crops in.
Cleistogamous flowers are self-fertile flowers that don’t open to become fertilised. In the case of violets, some flowers are cleistogamous and are produced underground whilst the rest remain above ground and appear as normal flowers. The Violaceae genus is the largest cleistogamous plant grouping.
I suspect cleistogamy evolved for two reasons. Firstly to save resources/energy. Producing petals, nectar etc takes massive amounts of energy.
From the French for a bell, a form of plant protection, the original ones were glass and made in the shape of a bell.
Today the range of cloches is much wider with continuous plastic-covered hoops that form a mini tunnel being available in many garden centres.
Recycled plastic bottles are often used as a form of plant cloche by many gardeners.
Plants that are produced asexually either as seed or via stem or root cuttings are clones of the parent plant. This means they have exactly the same genetic composition ie they are genetically identical.
Clones occur naturally in some species and are used as a means to reproduce. In some cases, they shed branches or twigs that can then root nearby. In other cases, they form clonal colonies. Elm trees are an example of reproduction by clonal colonies via suckering.
Dandelions are an example of a plant that is capable of a plant that can produce asexual seeds via a process called apomixis.
Some plants naturally form clumps rather than individual plants. They tend to be perennials.
Clump-forming vegetables include shallots and chives.
An unheated frame made of plastic or glass for acclimatising or growing on plants. Sometimes they are used in conjunction with a hotbed/compost bed to supply gentle warmth to a crop during the process of growing or acclimatising. The Victorians used cold frames in conjunction with hotbeds to grow melons and other crops that prefer warmth and bottom heat early in the season.
A fertiliser that contains all three of the major or micronutrients essential for plant growth, namely nitrogen, phosphorus and potassium. (N, P, K). Complete fertilisers are often referred to as General Purpose fertilisers.
Compost is composed of organic material that has decomposed in a process called composting. Those sold in garden centres has usually been composted on an industrial scale though it is easy to compost smaller amounts of organic matter on a garden scale.
Peat is also composed of organic material but is not normally referred to as compost. Indeed many composts are sold as peat-free composts due to the negative conservation issues attached to peat use.
Compost is nutrient-rich and if made well is free from pest, disease and weeds due to the high temperatures achieved during the composting process.
Composts include seed composts, ericaceous composts, loam-based compost, peat-based compost, organic compost, peat-free compost, leaf compost, potting composts, multi-purpose compost etc. All of these have slightly different purposes and makeup including pH and fertilizer levels
Compost is used as a soil conditioner, fertiliser and growing medium.
Always check the pack to see what it is recommended for and always try to use the right compost for the right job.
Try to avoid composts that include peat.
Check your soil pH before using compost as a soil conditioner.
When setting seed always firm the compost and water before sowing the seed. This prevents air pockets from forming and ensures that the compost is moist enough.
Composts can often be reused if additional nutrients are added. But ensure that drainage is not impeded in old composts that have “slumped”.
Don’t sow seeds in ericaceous or high nutrient composts as the conditions will be adverse in most cases.
Before replanting pot plants in new compost always soak the existing root ball in a bucket of water for at least an hour. Once repotted water again to settle the compost. This ensures it will not dry out in the new compost.
Unlike deciduous trees, coniferous trees keep their leaves during winter. This means they have to grow more secure roots to ensure they don’t blow over in storms.
A pot or other receptacle for growing plants
A fertiliser that has been manufactured as a prill of in other form designed to release nutrients in response to temperature or moisture stimulus
Crops that thrive in cool conditions. They dislike excessive summer temperatures which often makes them bolt. Excess heat slows down the enzymes that drive photosynthesis and slow plant growth.
Coppicing is an ancient woodland skill where species such as hazel are cut at, or close to, ground level. This stimulates more young growth from the “stool”. The cut growth was originally used for making fences, thatching spars and other sustainable products.
Coppiced woodland allows the sunlight in and this stimulates the growth of many species of flowering plants. Coppicing is normally undertaken on a cyclical basis. The length of the rotation used, in each coup (section of woodland), depends on the species of tree being coppiced. For example, birch was coppiced on a 3-4 year cycle to produce faggot for burning to heat homes and to cook over. Hazel produced the wood needed for the thatching spars, wattle, fences etc and oak would be coppiced on a 40-50 cycle that produced roofing and other construction timber.
Alongside the flowering plants that resulted from the coppice being cut came a range of wildlife, and the varied stage of growth in each coup provided rich biodiversity within woods. Woodlands that were traditionally cut over many years were often referred to as copses.
Cordon grown fruit include tomatoes. The plant, in this case, is sideshooted to allow a single cordon to dominate the growth. Cordon systems are used in commercial horticulture as a form of vertical growing.
An underground storage organ found on plants such as gladioli, cyclamen etc. Corms consist of a swollen stem base plus a number of scale leaves.
Very few vegetables form corms, examples that do include eddoe and taro.
Cotyledons; of which there are two sorts, monocotyledons and dicotyledons, are used to refer to plant seed leaves. in a wider sense, they refer to the two groups of flowering plant types that are defined by the nature of their embryonic seed leaves.
Examples include grasses and cereals which are monocots and plants such as the Solanaceae and Cucurbitaceae .. the tomato, pepper and potato family and the cucumber, marrow, squash family which are dicots.
Cover crops are normally grown when main crops are not being grown. They decrease erosion and can be used to increase fertility when ploughed in. For example, clover and other leguminous crops might be grown and dug in to increase fertility, especially nitrogen levels.
Cover crops may also be harvested for composting. This is of special interest when no-dig systems are employed.
Cover crops may also be grown as a nurse crop to protect and help weaker crops to establish in inclement conditions.
Mankind soon discovered that pests and diseases were more prevalent where the same crops were grown each year. Farmers therefore developed systems whereby crops were rotated. Hence they might only grow potatoes on a patch of land every 5-6 years. The other crops in the rotation would depend on the locality, altitude etc. In the warmer, wetter, west of the country grass for grazing animals would be included in the rotation. Elsewhere it would not and a typical farm rotation would be Turnips in year one, followed by barley which was undersown with clover and ryegrass. The grass and clover then lasted two years and helped to build fertility. Turnips could be replaced with potatoes if preferred. Sheep were an essential part of the process as they ate the turnips and grass and fertilised the soil with their droppings.
The above was referred to as The Norfolk Four Course Rotation and was revolutionary when it was developed as it replaced a fallow, and hence unproductive, year in previous systems.
An alternative was the Norfolk Six Course Rotation which consisted of corn, turnips, corn, corn, grass, grass. We can thank “Turnip” Townsend for the four-course rotation and Coke of Norfolk for the earlier six-course rotation which he developed on his Holkham estate. Today at Holkham they grow a new ‘Six Course Rotation’ of oilseed rape, winter wheat, sugar beet, winter wheat/spring barley, potatoes and winter barley/winter wheat.
Elsewhere, the ability of mankind to use chemicals to control pests, and diseases and fertiliser to control fertility, has led to monocultures.
On a garden scale crop rotations are still preached by many. However, I am among the increasing number of people adopting the No-Dig gardening system and I’m aware of crops being successfully grown on the same land for years. Eg. a colleague has grown potatoes on the same land for six years with no decrease in yield and no blight issue.
Cross-pollination refers to the need in some species for two or more plants of the same species to pollinate one anothers flowers if a crop is to result. It is necessary in contrast to self-fertile species.
Found in plants such as rhubarb and asparagus, the crown technically is the growing point of the plant from which new shoots emerge at soil level or just below. However, the word is also used to describe the whole plant when we buy rhubarb crowns or asparagus crowns.
Cultivar is short for cultivated variety and is commonly used to describe ornamental or decorative flowering plants.
A tool used to cultivate the soil
Cultivations are the mechanical process of turning and or breaking the soil to produce a seedbed. The word is sometimes expanded to include intercrop/row cultivations that are used to weed between plant rows.
Cultivations break the soil crust allowing both soil aeration and improved drainage/water penetration.
One of a series of ways to propagate plants. In this case, propagation is achieved via root or stem cuttings. Sometimes a rooting hormone powder is used to speed the growth of roots from the stem. Stem cuttings include softwood, semi-hardwood and hardwood cuttings depending on the species, time of year etc.
A cyme is a flower structure (inflorescence) where the central stem bears a single terminal flower and develops first, followed by all the other flowers in the inflorescence. Each of the lateral stems also terminates in a flower(s) coming from a terminal bud on the lateral. In the case of simple cymes, one flower occurs per lateral. In compound cymes the lateral splits and throws sub laterals, each having its own flower.
Examples of cymes include Elderflower (Sambucus), forget me not (Myositis), Stitchwort (Stellaria), Russian comfrey (Symphytum) etc.
Gardening Terminology – D
A fungal disorder whereby seedlings die due to the stem rotting off at soil level. Sometimes the seeds fail to germinate due to the same fungi. Prevention includes using sterile composts, good air circulation, clean water sources and ensuring the compost is not over watered.
The process of removing dead flowers to encourage more flowering. Seed production produces hormones that discouraged more flowers. Hence if the flower heads are removed there is no seed produced and more flowers will usually follow.
Deciduous trees and bushes are those that shed their leaves in autumn and do not regrow them until spring. The process is determined by cells within the abscission layer of the leaf – see abscission layer. This offers many benefits. Toxins that have built up in the lives are removed, the old leaves are then available for recycling back into the plant. In addition, the absence of leaves means that wind rock is reduced. If all the branches had a full contingent of leaves it would be badly affected by strong winds and storms and could be blown over.
Coniferous trees keep their leaves and need to anchor more strongly to the soil to ensure they are not blown over in storms.
Where a plant shoot eg the main stem in tomatoes, ends in a flower bud(s) it is said to be determinate.
In tomatoes this means that the main stem grows to a given height, usually with 5, 7 or 9 leaf axils before terminating in a flower truss. It then stops growing upwards and can not be trained as a cordon plant. It is in effect a bush, hence the term, bush tomato. In this form, each leaf axil consists of a leaf AND a side shoot. Each side shoot will also be determinate and will effectively make the bush even bushier.
A pointed stick or tool used to produce holes for plants. seeds or bulbs.
A botanical term to describe plants that have male and female flowers on different plants. The female flowers are unable to be fertilised without a male plant being nearby to enable pollen transfer via insects, birds, wind or whatever mode is employed.
The process of sowing or drilling seeds by hand or machine in their final positions. ie where you want them to flower or crop.
Large clumps of perennials often benefit from being divided every 3-4 years in autumn or early spring. This entails splitting the clump into a number of plants each with roots, stems etc.
Seed often exhibit dormancy at certain times of the year or until the right conditions are available. Eg. warmth, daylight etc.
Plants also become dormant at certain times of the year e.g. after leaf fall in autumn. Though plants appear dormant it is often the case that they are producing root underground and cannot be said to be truly dormant. This is why autumn planting of bare root and pot-grown trees is often more successful, due to the fact they have made root over winter and have established.
A fungal disease of plants characterised by visible “downy” deposits of spores on the underside of leaves.
Drainage aids the movement of water through the soil, which in turn pulls air into the soil as a partial vacuum is formed.
Many plants require good drainage or they will eventually “drown” due to there being inadequate oxygen for them to absorb.
A straight narrow furrow in the soil or compost in which seeds are sown.
Sometimes used to denote the row in which plants can be transplanted.
See also Broadcast
See Trickle Irrigation
Gardening Terminology – E
A common term in potato growing, though it can apply to other crops, where the soil is drawn up around the plant to protect from frost/exclude light etc. In potatoes, it may encourage more roots to develop from the stem that is covered.
Though not technically earthing up the addition of adding more grass clippings to No-Dig potatoes serves the same purpose.
A plant that is both edible and ornamental.
Electrotropism is a plant’s response to an electric field. For example, pollen tube growth is affected by an electric field.
In some cases, the electric field can have a negative or even lethal impact on plants and in some cases it is positive.
The section of stem above the hypocotyl, ie between the cotyledons and the first true leaves.
Ericaceous refers to lime hating plants that therefore require an Acid Soil or compost. Hence we have ericaceous composts that have been designed for them.
Plants in the ericaceous category include blueberries, heathers azalea, and rhododendron.
Ericaceous Composts are designed with a high pH to grow ericaceous plants. Eg. camellias, azaleas, rhododendrons etc. This is particularly useful when growing in pots, planters and boxes and to a lesser extent in beds and borders. In the later care must be taken to ensure that the pH changes with rainwater incursion.
Soil erosion is caused by rain, wind, water flow and wind and can seriously deplete soils. Bare soils erode much faster than those with vegetation or other cover and hence many growers and farmers grow cover crops at certain times of year to decrease erosion.
A form of pruning trees and shrubs that produce lateral growth at the expense of height. This makes fruit picking far easier. It also reduces competition between branches and increases airflow through the plant structure, often reducing diseases and improving ripening.
Etiolation is the technical word used when we say a plant is “drawn”. Etiolation in flowering plants happens when they are grown in poor, partial or complete absence of light. They respond with long, weak stems; smaller leaves due to longer internodes, and turn pale yellow in colour due to the lack of light (chlorosis). What we think is adequate light often isn’t enough for plants and they get very drawn in their search for better light.
Etiolation is the process of becoming etiolated.
The physical process by which liquid water returns to the air. It is speeded by higher temperatures and wind.
Evaporation is important in the process of transpiration.
A term used to describe some strawberry varieties that produce a small crop over a very long period, from spring through to summer/autumn. They often finish the season with a good-sized cropping spurt towards the end of the season.
Evergreen plants do exactly what their names suggest. They remain evergreen throughout the year, they do not shed their leaves. This is sometimes influenced by the climate and/or weather conditions.
Most, but not all, conifers are evergreen. Eg. the dawn redwood (Metasequoia glyptostroboides) is a deciduous conifer.
An exudate is something that “oozes” out of an organism. Inhumans terms that can be sweat, mucous, the liquid that oozes from a wound or pus from an infected wound.
In plant terms, it can be nectar, sap, gum, resin, latex or a root exudate.
Root exudate is particularly interesting as most people don’t know it exists, and yet it is vital for the microfauna surrounding the root. Root exudates include sugars, acids, and ectoenzymes that nourish the microorganisms surrounding the roots.
Seeds exude a number of chemicals into the spermosphere i.e the area that surrounds a seed as it germinates.
Exudates have commercial value in some cases. e.g. the latex of the rubber tree. Gums (and the essential oils) such as galbanum, which comes from a Persian grass, are used in perfume making and cookery. Galbanum essential oil is found in Chanel No 19, Miss Dior and Ralph Lauren’s Safari. The plant also produces the gum resin, asafoetida, which is used in Indian Cooking and perfumes.
The point from which stems or roots emanate on a tuber. For example, potato eyes are where the growth commences during chitting.
Gardening Terminology – F
The F1, or first filial generation, is the result of breeding together two distinct purebred lines. They often show Hybrid Vigour and produce very uniform plants. However, plants produced from their seed obey Mendell’s Laws and do not breed true.
The second filial generation.
See also F1.
In the classification or organisms, including plants, the family is the division that includes a number of similar genera.
A one-year-old tree that consists of a single main stem ANf edges D a number of side branches or feathers.
Often confused with fertilising. We feed a plant when we add nutrients to its soil/compost or water.
Another much misused gardening word. When a plant is fertilised it signifies sexual reproduction. It doesn’t mean the plant has been fed.
Plant food. Plants need a range of major, minor and trace nutrients to survive, grow and reproduce. The major ones are Nitrogen, Phosphates and Potassium that are usually represented as NPK. Minor and trace elements include magnesium, zinc, calcium, sulphur and iron.
Plant nutrients occur naturally in soils and composts but not always at a sufficiently high level to allow the required level of growth. Hence gardeners and growers need to add more fertiliser.
Where No-Dig is employed the plant nutrients come from the compost added to the surface and this is generally done once or sometimes twice a year. In other cases fertiliser may need to be added before planting each crop. It is then sometimes topped up during the growth of the crop.
Fertiliser can be purchased as organic or inorganic (artificial) fertilizer and can be in liquid or solid form. In many cases it needs to be broken down in the soil by bacteria and dissolved in water before it is available to the plant.
Although the idea of being organic appeals to many people, the plants can’t tell the difference between organic and non-organic fertilisers as they are taken up by the plant in exactly the same way.
When growing commercially and now on a garden scale I’ve used Vitax Q4 as a granular base dressing fertiliser for general use and Tomorite as a liquid feed for tomatoes, peppers, courgettes, aubergines, cues etc.
In botany, the filament is that part of the flower that supports the anther. Its a stalk or stem-like structure
Often used to describe flowers where it means frilly, fringed, or jagged. There is a category of Dahlias called Dahlia fimbriata.
A potato cultivation term. First Earlies are normally harvested in around ten weeks from planting, though the exact timescales will depend on chitting, soil temperature, planting date and other variables.
First early varieties are however the fastest maturing varieties and include Rocket, Orla, Red Duke of York, Pentland Javelin, Foremost etc. These are best suited for new potatoes or baby potatoes.
Horticultural fleece is a thin, light woven material with a high light transmission that can be used to cover crops. It reduces weather damage, keeping crops warmer and reduces pest damage by preventing access to butterflies, carrot fly etc.
Fleece comes on various weights, the heavier ones lasting longer. Fleece is permeable to air and rain.
Floricane growth is the second year’s growth of a cane that fruits in the second year. As opposed to a primocane which flowers and fruits in the first year.
Floricanes varieties are often described as flowering/fruiting on old wood.
A plant’s leaves are its foliage.
A Food Forest to Forest Garden is a collection of edible or useful plants grown in as near natural conditions as possible. It aims to mimic natural ecosystems with three-dimensional designs where the plants and food grow up, down and sideways. Hence the food produced can include roots, ground-level crops and high-level crops such as top fruit.
Forests, however, go further and seven layers are normally recognised. These include the
- Root Layer
- Ground Layer
- Vine Layer
- Herbaceous Layer
- Shrub Layer
- Understorey Layer and Overstorey Layer
- Some people also recognise an eighth layer, the Mycelial Layer comprising fungi of all sorts.
Typical food plants grown in food forests include Blackberries, Walnuts, Hazel, herbs, Passion Fruit, Kiwis, elderberry, rhubarb etc.
A word used to describe a soil that is easily crumbled or pulverised.
Probably the most obscure word in this dictionary, frim is an archaic and/or dialect word previously often used to describe soil that is in ideal condition for sowing or planting. Elizabethan poet, Micael Drayton, used it in a slightly different sense when he described “frim pastures”. By which he meant, flourishing, thriving or fresh pastures.
I’ve added frim as I still use this word and know of no other suitably concise to describe soil that is ready for sowing. Though tilth is used to describe the condition of tilled soil and cannot be used without a modifier to clarify the state of the tilth.
Typical of ferns and palms where leaves have multiple divisions. The term is often used to apply to large leaves but can also be used to refer to the leaves of small ferns and even algae where the small leaves are not divided! This is a word that can confuse some people!
Deadly to some plants, frost is formed when moisture freezes on the soil, lawns etc. Air frosts can result in moisture freezing in the air and on trees and other vegetation, resulting in beautiful wintery scenes.
Warm air rises and cold air descends. And when cold air is trapped in a hollow it sometimes results in a frost in the hollow/frost pocket. Frost pockets can occur on the sides of hills where a fence, hedge or dense planting of shrubs or trees restrict air movement. It is sometimes possible to negate a frost pocket by judicious removal of the obstruction.
A site that receives no direct sun during the whole growing season.
An area that receives at least 8 hours of direct sun each day of the growing season.
A substance or material that kills or controls fungi.
Fusarium is a large group of soil-borne, filamentous, fungi. Some are problematic in gardening and agriculture. Eg Fusarium Wilt in turf and Fusarium Ear Blight in wheat.
Fusarium Patch, commonly referred to as snow mould, is a common fungal disease of turf and lawns. Its caused by a soil-borne fungus, Microdochium nivale, which also colonises cereal ears in cool moist weather.
Gardening Terminology – G
A group of closely related plant species or other organisms. It sits between species and family.
Literally translated as “earth eater” geophagy is the lifestyle adopted by some earthworms, ie those that derive their nourishment from organic matter in the soil. There are actually four worm ecotypes with many soils having more than one type present. Specialist eco-niches such as compost heaps and related naturally-occurring habitats have their own ecotypes often referred to as compost worms e.g. “Tiger worms”. however, these are not geophagous as they don’t eat soil, preferring to eat rotting vegetation/organic matter. True geophagous earthworms are omnivores and consume both plant and animal material contained in the soil.
Geotropism, sometimes called gravitropism, is the response of plants to gravity. Stems grow upwards away from gravity and are said to be exhibiting negative geotropism. And roots grow downwards towards gravity and are said to be positively goetrophic.
Germinate / Germination
The process where a seed starts to grow.
The process where one plant is joined to another. This is normally done to control growth. E.g a vigorous apple variety will be grafted on to a dwarfing rootstock. Or a Victoria plum, which is a tall variety, could be grafted to a St Julien A rootstock which is semi-vigorous, hence creating a tree more suited to a small garden.
Tomatoes may also be grafted and the adverts say they then crop more vigorously. However, as a retired commercial tomato grower, I believe most amateurs can achieve the same yields by adhering to good growing practices and need not pay extra for grafting that will offer them few benefits.
The failure of a graft to “take” is often due to a number of reasons including incompatibility of rootstock and scion. Closely related species, cultivars and varieties ar easier to graft than those that are unrelated.
In conventional growing, this is a crop grown to be ploughed back into the soil. In No Dig gardening, the crop can be incorporated by smothering it under a black sheet or similar until it dies.
Green manures offer many benefits including the prevention of erosion, the addition of organic matter, incorporation of nitrogen when leguminous crops such as clover are grown. In essence, the aim is to increase soil fertility. Legumes are often used as green manure due to the fact they add nitrogen to the soil.
A low growing plant that covers the ground. It can be as a feature plant or used as green manure. In both cases it can be used to smother out weeds.
Species typically used in the UK include vinca, hedera, thyme, juniper, ajuga, chamomile, pachysandra, and creeping cotoneaster.
The period of time during which growth occurs. It varies from place to place depending on first and last frost dates or winter thaw. Each species has slightly different growth requirements so some may start to grow earlier or later than others. Altitude, frost pockets and other factors affect the length of the growing season in specific locations.
For example, as we ascend hills the temperature drops approx 6 degrees C for every 1000 metres / 3.3 degrees F for every 1000ft
Gardening Terminology – H
An annual that is not fully frost hardy and needs some frost protection and hardening off before being planted out.
A plant that goes through its full life cycle in two years but requires frost protection as it is unable to tolerate temperatures below 0C.
A plant that grows from one of the underground storage organs listed above that requires frost protection in winter. In some cases, they will also require protection from excessive moisture and are best lifted and stored dry indoors.
Halotropism is the ability of a plant to directionally grow in response to salt concentration. It’s a relatively underinvestigated form of tropism and the first scientific reviews I can find are from 2013. In their paper, Halotropism Is a Response of Plant Roots to Avoid a Saline Environment, Galvan-Ampudia et al report on their work with Arabidopsis, tomato, and sorghum seedlings and how they prioritised growth away from a salt gradient.
The process where plants become acclimatised to new conditions. It usually applies to plants grown indoors or undercover being moved outdoors but can also apply to plants being brought in from cold conditions to warm dry conditions.
Hardening off is a slow process and best done in steps.
The USDA in 2012 produced a Plant Hardiness Zone map based on average annual minimum winter temperatures for the USA. It’s based on 10 degree F increments and we can produce similar maps internationally for other countries.
Where I live in Sidmouth, Devon, UK, my zone is 9A which means it’s pretty mild here. We are just a mile from the sea and frosts are not normally severe, though we must remember that the zoning is based on average temperatures and some will dip well below those indicated as an average.
The elements of a garden’s design that are non-plant. E.g. paths, walls, buildings, patios etc. They form the skeleton of a design and are generally installed before planting is undertaken (though they may be added to an established garden years after it is established).
A herbaceous or shrubby plant that persists for more than two years and is tolerant of winter conditions. Eg low temperatures, snow, wet etc.
A woody plant capable of withstanding winter conditions eg cold, wet, snow etc. Trees and shrubs are normally described as having a permanent framework of branches that do not die back in winter, though they may be deciduous.
Normally applying to potatoes, the haulm is the leaves and stems of the plant.
Heavy soils contain a lot of clay and are generally poorly drained and cold.
Plants such as young sunflowers exhibit heliotropism when they follow the sun, from east to west, as it crosses the sky. This increases the amount of sunlight hitting the flower and increases pollination rates. Some plants are able to return the flower to an east-facing position overnight, ready to gain the greatest benefit from the sun.
A herbaceous plant is non-woody and therefore dies back in winter before resuming growth in the spring. The dormant period is survived as a root.
In some cases, the term can also refer to plants that die back at other periods of the year due to adverse conditions. Eg during the dry period, which then equates to the European winter.
A product or substance that kills or inhibits plant growth.
Heterorhabitis bacteriophora is an entomopathogenic nematode that predates a wide range of insects including ants, fleas, moths and weevils.
The sweet clear substance excreted by aphids and other sap-sucking insects. It is produced from the excess sugars consumed by the insects as they seek nutrients from the plants. Some ant species”farm” aphid for their honeydew, giving the aphid protection from predators in return for honeydew.
A person with extensive knowledge of gardening and/or plants, their cultivation and care.
Though intensely studied humus is often ill-defined. It is perhaps best defined as the amorphous product of degraded compost. Ie the dark spongy matter that is left when compost breaks down and no longer has a well-defined composition. It includes animal, plant and microbial remains that have been mechanically degraded but retain their chemical composition.
Humus is an important part of soil organic matter and important as a moisture reservoir.
The offspring of two unrelated individuals within a species leads to improved function of a given trait. Referred to as hybrid vigour is is akin to improved genetic quality to biological fitness.
Another term used for this form of genetic crossing is outbreeding. The opposite, inbreeding, probably explains the concept best.
A growing technique using water and nutrients without soil or compost.
Hyrotropism is a plants response to water concentrations. When root growth moves towards the water, such as during drought, it is said to be exhibition positive hydrotropism. When soils are saturated and the plant grows away from the water it is said to be exhibition negative hydrotropism.
The hypocotyl is the part of the seedling that is between soil level and the cotyledons.
See also Epicotyl.
Gardening Terminology – I
A term most often found describing tomatoes and the opposite of determinate. Where the stems or shoots do not terminate in a flower bud or flower truss. Hence indeterminate tomatoes can be cordon trained, as opposed to determinate bush varieties. Cordon trained indeterminate tomatoes are not limited in their height and in commercial tomatoes growing often reach 30 foot or more and are grown as layered plants to keep them accessible for picking.
A product or substance that kills insects.
IPM is widely used in agriculture and commercial horticulture, and can be employed in gardening as well. It uses a wide array of methods to combat pest and diseases including cultural practices, natural predators and parasites, pest/disease-resistant varieties, pesticides (if all else fails), biological control and physical techniques such as fleece etc.
IPM is not organic but tries to minimise the use of pesticides wherever possible.
Intercropping is the growing of two crops on the same plot of land simultaneously. This can be done to save space because the two crops benefit one another by virtue of encouraging insect predators or providing protection from the weather. In this article and further linked articles, I’ll also discuss other reasons as well as linked concepts such as mutualism and resource partitioning.
An example of intercropping in gardens would be the planting of brussel sprouts between the rows of potatoes a few weeks prior to harvesting the potatoes. The theory is that the sprouts establish before potatoes are harvested. My personal observations are that whilst this can work if the potatoes are dug very carefully, this leaves a very loose root run for the sprouts. Brussel sprouts prefer firm soil to anchor their roots in or they will blow over in strong winds.
A better example might be to plant rows of lettuce between tomato rows a few weeks prior to the toms being ripped out. If the toms are adequately deleafed there is enough light for the lettuce. And if the toms are cut off at ground level, leaving the roots in the ground (they eventually break down and encourage drainage), the lettuce thrive and can mature very shortly after the tom crop is removed. Indeed if we practice cut and come again they can start harvesting before the toms finish.
Another example is to sow fast growing leeks between french beans so that as the beans finish the leeks then grow and mature as baby leeks a few weeks later. For this to work I recommend a fast-growing baby leek variety such as Nipper.
My last example can be considered as interplanting or undersowing. It is to sow green manure on the land before removing the “nurse crop”. For example, a crop of red clover or mustard could be sown between rows of many crops prior to harvest. Crops such as lettuce and French beans are ideal nurse crops as they can be cut off at ground level without disturbing the green manure.
The advantage to using clover as the green manure is the fact it adds nitrogen to the soil provided we leave the roots in situ.
There is a difference between intercropping and interplanting in my mind, though many people consider them as being the same. For me Interplanting is a temporary process as illustrated by the Brussel sprouts example above. The plants share the same space for a short period of time. Intercropping is different. I define it as being two crops sharing the same space and being harvested whilst sharing that space. An example would be to grow climbing beans with a crop of maize or sweetcorn. The sweetcorn provides support for the and both are harvested in situ before they are both ripped out at the end of the season.
Forms of Interplanting & Intercropping
This is the classic example where the second crop matures after the first has finished. Eg the Brussel sprouts and potatoes cropping.
Where two crops are mixed together in a random way (in other words not in rows). This is common in flower beds but less so in veg gardening. It can include two varieties of the same crop eg different colour carrots or beetroot. Or it can involve mixing different species together. An example would be mixed winter cropping as sold by some seed companies. Here they mix things like Chinese cabbage with Swiss Chard, Lettuce, Rocket and/or other mixed leaves.
The traditional Aztec Three Sisters of sweet corn, beans and squash grown in rows is a typical row Intercropping practice.
A plant that invades or has the potential to do so. This can include ornamental plants or those normally termed weeds. Eg some bamboos can become invasive as can rhododendron. Himalayan Balsam is an invasive “weed” often seen in hedgerows and next to waterways.
The process of supplying water, and sometimes liquid feed, to crops. Systems range from water channels, irrigation systems such as Overhead, Trickle (Drip) and Rainguns, as well as low tech solutions such as watering cans!
Gardening Terminology – J
The John Innes Centre is located in Norwich, Norfolk and is an organisation focusing on plants, plant genetics, and related microbial sciences. The organisation commenced in 1910 as the John Innes Horticultural Institution and was then based in South London.
These composts were developed at the John Innes Centre and are soil-based composts used in a range of horticultural situations. The compose a seed compost plus a range of numbered composts designed for specific purposes.
Gardening Terminology – K
The chemical symbol for Potash, a major plant nutrient and fertilizer component.
Gardening Terminology – L
In the UK land is divided into five major classes, from class 1-5. Class one is the best land, very fertile, able to grow the best crops and is the most expensive. It is predominantly found in river valleys and in the predominantly vegetable growing areas of Lincolnshire. They are usually alluvial soils, predominantly silts. The other class one lands are peat-based. In both cases, they must be well-drained and not prone to flooding or they would not be regarded as class one.
Class 5 is very poor land, unfit for growing agricultural crops, often flood-prone.
Class 3 land is subdivided into several subsets and is “average” land with various characteristics.
The process that includes design, planting and installation of hard landscaping within the environment. Normally the process focuses on individual gardens but may apply to whole landscapes.
Landscape design and building combinations are perhaps best encapsulated by the work of historical characters such as “Capability” Brown, Hubert Repton and Edwin Lutyens who worked with Gertrude Jeckyl on joint architectural and landscaping projects such as Great Dixter, Munstead Wood and Castle Drogo. The latter was implemented whilst luychens was also working on the design for New Dehli.
A lateral bud forms in the apex between the stem and a leaf petiole. Lateral buds grow into shoots such as tomato side shoots.
Latin plant names
See Botanical names, Linnaeus and The Beauty and Meaning of Latin Plant Names
A propagation method where a low hanging branch or shoot is secured in the soil, whilst still attached to the parent plant until it forms roots and is able to be detached from the parent plant.
Leaves take a long time to compost but make an excellent rich compost that is dark and earthy. It is very moisture retentive and is an excellent addition to other composts where moisture retention needs to be improved.
To make leaf mould leaves should be collected in autumn and held in a compost bin constructed of chicken wire. Alternatively, some people suggest you collect the leaves with a lawnmower as this shreds them, add them to a large plastic bag, wet them thoroughly, tie the bag neck, pierce the bag for drainage and leave for two years.
I find both methods work. However the former works quicker if you turn the leaves a few times to aerate the heap.
Leggy plants are those with abnormal stem growth making them look like they have long legs. This results in floppy plants that are often unable to support their own weight. It is often the result of poor light conditions that have caused the plant to become etiolated.
Leggy transplants can often be planted deep tp overcome the issue. This is especially true of tomatoes. pepper, and similar warmth loving plants,
Calcium compounds of various sorts are referred to as lime. They are generally used to reduce soil acidity and can persist for long periods in the soil.
Some soils are chalk-based and hence “lime-rich”.
Carl Linnaeus is known as the Father of Taxonomy. His work led to the naming of organisms by an organised naming system that used two names (binomial name) to classify and describe organisms.
The binomial naming system makes use of a range of languages but notably uses Latin to describe the features of many organisms. Eg. Digitalis purpurea (purpurea is Latin for purple).
Loam is a mix of predominantly sand and a smaller quantity of clay particles along with other soil particles. The proportion of sand to clay subdivides loam into sandy loam, silty loam, sandy clay loam, silty clay loam and clay loam.
Loam-based composts have a percentage of loam added to them. This makes them heavier, hence less likely for pots to blow over, and less likely exhibit rapid temperature fluctuations.
Gardening Terminology – M
Minor plant nutrient. Where plants suffer a deficiency it can be remedied by a foliar feed containing Epsom salts.
Organic material from the farmyard. The droppings of farm animals, normally mixed with straw or other bedding materials.
See also Green manure.
A fungal disease found on many plants but especially cucurbits such as cucumbers, marrows, courgettes, squashes etc. The visible growth looks like a white powder on the leaves and eventually the leaf yellows and dies.
Though it looks catastrophic plant growth in crops such as cues often outpace the mildew and they don’t succumb totally. In fact, I’ve often had cues with mildewed dead leaves on the bottom of the stem but strong growing productive growth at the top.
A very small insect pest that is sometimes found sucking sap on the undersides of leaves.
A product that kills or controls mites.
An organic layer of material that is spread over the surface of the soil, between the plants, to control weeds, hold in moisture and, in most cases, to improve fertility. Materials used include compost, spent mushroom compost, woodchip, straw, leaves, leaf mould, grass mowings, etc.
Multi-purpose compost comprises more than one compost, each with varying constituents. Some will be enriched with nutrients and some not. They may be organic or not and may be peat-based or not. Some will have John Innes added. So look on the pack to see what each pack is recommended for a most don’t really live up to the name multi-purpose!
When plants are grown close together many people consider there to be benefits to both crops. This might include pest control where one crop attracts predators to a pest on the other. I discuss this under Beneficial Insects
In other cases it is claimed that a crop can deter pests that depend on smell, from another crop.
An oft-quoted example is the planting of Tagetes (french marigolds) with tomatoes where it is claimed that the smell of the tagetes confuses whitefly that then doesn’t target the tomatoes. another would be the growing of alliums to deter carrot fly.
Research is not totally supportive of the above ideas. Indications are that it works in only 53% of studies.
Gardening Terminology – N
A plant that was, or is, found in a specific place. Eg potatoes were native to the Andes.
Nematodes are microscopic parasites of a range of garden pests. They offer the opportunity to use biological control methods rather than chemical control methods in the garden and on the farm.
Eg include the Slug nematode Phasmarhabditis hermaphrodita, Steinernema kraussei used to control vine weevils, Steinernema feltiae as an ant and leather jacket control, Heterorhabitis bacteriophora to control Chafer grubs, or you can buy a mix of nematodes in one pack that will control:-
- carrot root fly
- cabbage root fly
- onion fly
- sciarid fly
- shore fly
- gooseberry sawfly
- codling moth
A naturally occurring form of nitrogen found in the soil. It is produced via nitrification, where ammonia is converted into nitrates.
See also Nitrites and Nitrogen
The intermediate form of nitrogen that occurs in nitrification as ammonia converts to nitrates.
Nitrogen is a major plant nutrient required for growth, especially of green material such as stems and leaves. It occurs naturally in the air and at low levels is dissolved in rain. Leguminous crops produce nitrogen in association with nitrogen-fixing bacteria in root nodules. The nitrogen is available to the leguminous plant eg clovers, beans, peas etc. when it is growing and is released and made available to other plants when the leguminous plant dies.
Nitrogen fixation is the process, carried out by soil microorganisms. Some of these soil microorganisms have a symbiotic relationship with certain plant groups, notably legumes.
A gardening technique that involved no digging or ploughing of the soil. A mulch is added to the soil surface which suppresses weeds and feeds the soil and hence plants. Plants are sown direct or, preferably planted by using plant plugs/modules and a dibber.
No Dig has much to commend it, especially reduction in labour and effort to prepare the soil, and elimination/suppression of weeds.
In the first year, many practitioners lay cardboard on the soil surface and then add mulch as this further inhibits weeds in the first season.
A species that does not originate from where it is now growing.
See No Dig Gardening
The basics of plant food including the major nutrients, nitrogen, phosphorus, potassium, plus the micronutrients and trace elements required for plant growth. Nutrients are supplied by the soil via the decomposition of soil constituents and organic matter. Alternative sources include natural and artificial fertilisers.
Nyctinasty is the movement plants exhibit in response to their circadian rhythm as opposed to a tropism. It can apply to both leaves and flowers but not all plants demonstrate nyctinasty.
Examples can be seen in most legumes that close their leaves at night and reopen in the morning. This isn’t in response to light but is controlled by the plant’s circadian rhythm .. take a pot of legumes into a darkened room and they will open in the morning despite there being no light.
The speed at which the flowers or leaves close and open is quite slow so watching for it to happen is doomed to failure .. it’s like watching for the tide to change! But suddenly an open flower is closed .. and the tide is going out!
Gardening Terminology – O
Plant species that are pollinated by natural processes. Eg through insect, bird or animal activity, wind, etc. These plants tend to breed true as opposed to F1 hybrids that do not.
A substance derived from living material. One that is not manufactured from non-living substances. Can refer to fertilisers, etc and the foods produced from them.
It is often claimed that organic foods are healthier. However, though the cultivation practices may appear to be healthier it is a fact that not all organic materials are safe, Eg nicotine used as a pesticide can be highly toxic to humans.
Conventionally grown foods can, and do, offer the same nutrients as organic foods. However, the flavour is sometimes better, though the reason for this may be more to do with the cultivation and feeding methods than the fact it is organic.
The organic gardening movement is exemplified in the UK by Garden Organic, the Coventry based charity previously known as the Henry Doubleday Research Association (HDRA).
Garden Organic and similar organisations believe that crops should be grown organically, without the use of pesticides, artificial fertilisers etc whilst embracing natural growing cycles to enhance growth and the environment.
Because it is made from degraded organic matter people often think that all composts are organic. However the vegetable matter the compost was made from is rarely organic in the Soil Association sense of the word. In addition various chemicals may be added as fertilisers. Being made from organic materials does not necessarily mean the compost is organic.
Soil Association certified organic composts are available from specialist producers.
Organic matter is a carbon-based material composed or the remains of plants and animals and their waste products.
The organic matter in soils is derived from degraded plant and animal material plus microorganisms. Organic matter is desirable as it retains moisture and essential plant nutrients.
Plants grown primarily for their decorative or aesthetic value as opposed to being grown for consumption, medical purposes, fibre or other economic use. Some plants can be both ornamental and decorative. Eg the olive tree, cherry trees etc.
An irrigation sprinkler suited for small gardens consisting of a perforated curved bar sprinkler that oscillates as it sprays water over a plot. The jets of water tend to break up as they hit air resistance and the resulting drops resemble rain.
The gynoecium, or female, part of a flower.
Overhead irrigation is the term used to describe a number of irrigation systems used in greenhouses and tunnels. It consists of pipework and nozzles situated at a high level. When activated a raindrop type pattern of water results due to pressurised water hitting the spray head and breaking up into droplets.
Spray patterns tend to be uneven unless the system is well designed with the water being sprayed in a series of overlapping concentric rings. However, it is still one of the most effective watering systems available to the majority of commercial and amateur growers.
Gardening Terminology – P
A soil pan is a dense stratum or layer in the soil which is largely impervious to water and hence leads to waterlogging of the soil. They can be formed by compaction where a rotavator or plough has been used in wet conditions and have smeared the soil, causing it to pan. Surface panning can occur on lawns where the compaction is due to pedestrian to vehicular traffic compacting the surface.
An organism that lives on or in another organism so that it might obtain nutrients at the host’s expense.
Parasitic and semi parasitic plants include broomrapes and mistletoe. Parasitic plants use haustoria to enter the root and other vascular systems to derive nourishment from the host.
Partially decomposed vegetable matter produced in bogs, fens and other acidic wet environments.
Until recently peat was commonly dug, dried and sold as a compost for growing plants. Digging peat destroys rare habitats and is now largely stopped after environmentalists highlighted the problem.
Peat soils are farmed in areas such as the Fens of England and are extremely productive.
Some soils have a mix of peat in their composition, usually where a thin layer of peat has been mixed with other soil types as they have been farmed over centuries.
Peat-based compost is less common these days due to environmental concerns. At one stage it was the most common compost available to commercial and amateur growers.
Peat-free compost is available from many sources as are reduced peat mixtures. Peat free was problematic when first introduced as it suffered poor drainage and variable quality. That is now largely a thing of the past.
If the pack doesn’t specifically say peat free it is highly likely to contain some peat.
The pedicel is a small stalk in an inflorescence of flowers. Ie a sub stem. In tomatoes, it becomes the tomato fruit stalk and has an abscision knuckle when it naturally breaks during picking.
The peduncle is a stem-like structure that branches into a number of pedicels. They occur in tomatoes when we have split trusses or multiple branching trusses as commonly found in cherry tomato
Petals form the corolla of the flower. They are modified leaves, often brightly coloured to attract pollinators, that surround the reproductive parts of the flower. Though we see a range of colours when looking at flowers, insects including bees, see much more including what are referred to as nectar guides. Nectar guides are seen as ultraviolet markings that lead the bees to the nectar.
Perennials are long-lasting and may seed many times during their lifetime. Trees are a prime example, think how many acorns an oak will produce in a lifetime that spans centuries. So fruit trees, fruit bushes and even strawberries are perennial. But we aren’t limited to fruit. Perennial kale and asparagus have long lifetimes and keep producing fruit, leaves etc.
Perlite is a naturally occurring material that is used in horticulture to hold water in composts and for various other reasons, especially where its very light weight confers advantages. It is white and looks like polystyrene.
But don’t think that because it is natural it is a green material. It is produced by heating volcanic rocks to very high temperature so that the rock pops like popcorn! It is an energy consuming process and in my mind is questionable. It is also a finite produce and its use is unsustainable long term
Pesticide is the generic name for a group of substances, materials and products that kill or inhibit pests, diseases etc. They include aphicides herbicides, insecticides, fungicides, nematicides, piscicides, molluscicides, avicides, bactericides, viricides, rodenticides, etc. plus all the products and materials, such as repellents, that inhibit pests and diseases.
The word pesticide is often regarded emotively as they are considered to be “chemicals” and therefore not good! However, water is a chemical and we all need that. And we all need salt in our diets, but it can be used to kill slugs!
So the use of the word pesticide needs to be more thoroughly considered.
Pesticides can be natural or manufactured, organic or inorganic. For example, pyrethrum is a naturally occurring insecticide produced by plants of the pyrethrum family. But pyrethroids are products, based on pyrethrum, that are manufactured as an insecticide. Both kill insects.
And organic products may be natural but can be highly dangerous. For example, nicotine is permitted as an insecticide by the organic movement. It is however highly toxic to humans and can be absorbed via skin contact.
Many years ago I saw a well-known member of the organic movement making up a nicotine wash for his fruit trees. He was stirring it with his bare hands. He’s dead now!
OK, the nicotine didn’t kill him immediately but it can kill within hours if a lethal dose is absorbed. And he did die of heart failure a few years later.
pH is the measure of the hydrogen ion concentration in a substance and is used to measure the acidity or alkalinity of soils. ph 7 is regarded as neutral with lower numbers being acid and higher numbers being alkaline. Most plants prefer neutral or near neutral soil. Ericaceous plants prefer acid soils and there are also plants that prefer alkaline soils are thrive on chalklands.
Phasmarhabditis hermaphrodita is the slug nematode often recommended as a natural molluscicide. It’s the organic way to limit slug and snail damage, without resorting to chemicals. There’s a lot more detail at the following link.
Many seeds are photodormant which means the need to be exposed to light before they can germinate. This effectively means that a seed that is in the ground needs the soil to be disturbed, and light let in, to break its dormancy. The length of time, and intensity of light required, is minimal in both cases.
Photosynthesis is probably the most important chemical reaction on earth. Although it happens in plants, we would die without it.
It’s the process that drives plant growth. In photosynthesis carbon dioxide is taken from the air, water from the roots and energy from sunlight to produce oxygen and glucose via an endothermic process.
The carbon dioxide is taken in via stomata which are mainly found on the undersides of leaves. Oxygen is then given off via the same stomata. All life depends on photosynthesis. And in producing oxygen the plant absorbs large amounts of carbon dioxide.
The glucose that is produced is used to form more complex carbohydrates, such as cellulose, to enable plant growth. Some glucose is stored in special organs within the plant. For example, the tubers of potatoes, where it is converted into starch.
In all chemical reactions like photosynthesis, there are limiting factors. For example, a lack of carbon dioxide can prevent the plant growing as fast as it might and when I grew tomatoes commercially the concentration of CO2 in the air was low enough to make supplying additional CO2 to the plants and economic option. Today, with global warming, CO2 levels are higher. Temperature can also be a limiting factor. Too cool and the plant enzymes that help drive the process are slow, too hot and the enzymes denature and no longer work. Hence temperature is a critical factor, as is sunlight, in plant growth.
The following video explains this very clearly (its a GCSE biology video designed for school children … but though it feels like being back at school it is actually a very good explanation of photosynthesis and worth watching.
Phototropism is the directional growth process in plants where they respond to light. Positive tropism is seen when leaves, stems and to much lesser extent branches, grow towards the light. Roots often demonstrate a negative phototropism response.
Heliotropism is an associated process but is not primarily governed by phototropism.
Phosphorus / Phosphates
Phosphorus is a major plant nutrient that normally occurs as a phosphate. It is essential for healthy plant growth including the production of oils, starch and strong root systems.
though phytophthora is normally species specific
Phytophthora quercina causes sudden Oak Death when it infects the roots of the Oak trees.
A large fungal genus containing many pathogens. Phytophthora causes significant economic losses to growers and is at the heart of many horticultural disasters. E.g Phytophthora infestans is the pathogenic agent that causes potato blight and lead to the Irish Potato Famine.
Though phytophthora is normally species or genus specific, P. cinnamomi, P. cryptogea , and P. drechsleri have all been isolated in table grape death in Chile.
Phytophthora quercina attacks the roots on oak trees and causes Oak Death.
The process of removing the growing points of plants to encourage bushier growth. Pinching out stimulates side shoot growth. Side shooting is the opposite of this process and encourages the growth of a single leader.
The female part of the plant. Ie the seed bearing part of the plant that consists of the ovary, style and stigma.
Plant Hardiness Zone
Plugs are a pot or tray replacement when growing young plants from seed or cuttings. They enable significant growth to be achieved before the plants are transplanted. Hence they save space, ensure higher germination and growth rates and speed growth.
The shoot that comes from the germinating seed.
Aerial roots that are used to obtain oxygen from the air when underground roots become waterlogged. Frequently found on mangroves, banyans there are sometimes apparent on Schleffera, Ficus benjamina and rarely on brassicas and tomatoes.
Pollarding is a tradition forestry or woodland practice whereby the branches are removed for firewood or construction use. The subsequent regrowth is then above the grazing height of deer and other browsers. Though they look severely damaged pollarded trees, such as oak, soon send out new shoots and with a few decades can sport impressive regrowth.
Pollarding mimics and stimulates the natural regrowth ability of trees to recover after storms or disease remove large branches.
The process of pollen transfer from stamen to pistil. The process of fertilisation involving the fusion of male and female gametes to form a zygote.
Potassium is one of the three major plant nutrients and has a role in producing flowers and fruit, fight off disease, produce proteins and aid in photosynthesis
A compost designed specifically for potting on plants or seedlings. Potting composts can be organic or not and are normally enriched with additional nutrients, often with slow-release fertiliser.
To move a plant from a small pot to a larger one.
To pot seedlings up is to remove them from the seed tray and put in a pot or other container for them to grow on in.
To take seedlings from trays and replant into pots, containers or the soil.
Primocane varieties of crops such as raspberries, blackberries etc flower / fruit on new wood. Ie wood that has grown that season, as opposed to floricane cane that fruit on “old wood”.
The varieties of raspberries etc flower on first year canes/wood and are therefore usually autumn fruiting. Raspberry varieties include Autumn bliss.
The removal of plant material, usually branches and other laterals, but sometimes roots, from woody plants. Secateurs are the tool normally used to prune but saws can be used for larger material and knives for smaller material.
A genus of disease causing pathogenic fungi similar to phytophthora.
Gardening Terminology – Q
Quercus (Latin) is the name of the genus of trees commonly referred to as oaks. There are around 600 members in this genus which is part of the Fagaceae family.
Quinoa (Chenopodium quinoa) is a plant grown for its seed and is regarded by some as a superfood. The reality is that it’s been farmed for human consumption in Peru of 3-4000 years and prior to that as animal fodder.
It’s from the Amaranth family which includes Fat Hen (Chenopodium album) which was grown in the Iron Age as a food crop in the UK. The Vikings and Romans also harvested it.
Gardening Terminology – R
Racemes are flower inflorescences where the flowers are on a single stem, with each flower in a short stalk or pedicel, arising from the stem. The single truss of tomatoes is racemous. However, where the truss is split it is then known as a cyme.
The root that comes from the germinating seed.
Raingardens are a garden design feature that temporarily retain storm water after periods of high rain fall and allow them to slowly evaporate or percolate away. They prevent flooding and are useful in helping to prevent CSO incidents.
Rainguns are used in outdoor irrigation of vegetables and other high value crops. Static and mobiles systems are available. In both cases, a jet of water is sprayed over the crop after hitting a deflector plate which breaks it into droplets. The result is a mist of fine or larger droplets that resemble rain.
Mobile systems pull the irrigation head across the field at a steady pace and the spread of water is therefore relatively even across the area irrigated.
Raised beds are used to elevate the soil surface above the existing level. The advantages are said to include better drainage, a warmer growing medium and better aeration than conventional growing. They are of particular use where there is no soil due to rock strata being at surface level and where we wish to grow crops in concrete yards etc.
The counter argument is that they are expensive to build and maintain, harbour slugs and other pests, tend to dry out and frequently overheat in hot weather.
The base of the flower structure from which other structures arise. In strawberries and poms, the receptacle becomes the edible “fruit”.
The Relative Humidity or RH is the amount of moisture in the air compared to the moisture it could hold at that temperature.
Most people think roots are only found underground. They are wrong.
Whilst roots are normally underground organs that the plant uses to anchor itself firmly in situ, feed through or store food in, they are sometimes found on the soil surface or even above ground.
So the best definition of a root is to say it is an organ that doesn’t bear leaves AND does not have nodes. If it were non-leaf bearing, but had nodes, it could be a stem, so that’s why I include the last part of that definition!
Roots are extremely important to humans and many animals because we eat roots. As food storage organs in many plants, they swell to a good size and can be harvested. Think about carrots, parsnips, beetroot, and dozens of other roots we eat, and you’ll see what I mean.
You’ll notice I didn’t include potatoes in my list. It’s not a root, it’s a tuber, modified stem.
And to put the idea that roots live underground to bed think about aerial roots on plants such as mangrove. They keep the plants above the water and are used to exchange gases such as oxygen. Many orchids also depend on aerial roots and many never “root” into the soil. They derive their moisture nutrients direct from the air high up in the trees in places such as rain forests.
Many plants in the UK also depend on aerial roots. Ivy is a good example. Their aerial roots anchor it to walls or tree bark as it climbs.
Some roots help plants move! No, I’m not talking about triffids. I’m talking about contractile roots. Plants such as gladioli use them to pull the corm deeper into the soil if it is planted too shallow.
The parts of roots we normally see are the taproots and lateral roots (however some plants exhibit a different structure and grow fibrous roots E.g. many grasses). The taproot is the one that usually sits below the trunk or main stem of the plant and often goes straight down. The laterals are the ones that come sideways out of the taproot and anchor the plant in place.
The finest root are called root hairs and are extremely small. They absorb moisture and nutrients from the soil. Being so small root hairs greatly increase the surface area of the plant in contact with the soil constituents.
Root hairs are common to most types of root. However, in addition to fibrous roots, some plants have developed rhizomes or stolons.
Rhizomes are found in plants such as grasses, galangal, ginger and lotus. They are able to grow into new plants if removed from the parent plant and are therefore used for propagation in some cases. Rhizomes are essentially a modified underground stem that is capable of sending out roots and lateral shoots.
Plants frequently propagated from rhizomes include ginger, asparagus, hops, cannas, and lily of the valley.
Stolons are slightly different in that they emanate from an existing stem (though often very close to the soil surface). An example would be a strawberry runner, which is typical of this type of growth. It has long internodes and produces a new shoot that subsequently roots into appropriate media. In the case of the strawberry the stolon then extends and repeats the process, producing many new plants from the parent plant. Stolons are another potential method of plant propagation and often used by gardeners with strawberries.
Water is sometimes stored in roots and have been sought by hunter-gatherers in arid regions for this purpose. John Harberger describes several species including a Javan fern, Nephrolepis tuberosum.
Haustoria are a rather unusual root form. They are found in parasitic plants such as dodder and broomrapes as well as mistletoe which, because it can produce chlorophyll, is a partial parasite. The haustoria are developed to penetrate the roots or other plant parts of the plants they parasitise, to enable them to access water and nutrients.
Root Nodules & Nitrogen Fixation
Some plant species, especially legumes, are capable of forming a symbiotic relationship with bacteria (often rhizobium species). this results in nitrogen nodules being produced on the hosts roots in return for nourishment provided by the host for the bacteria.
A fungal disease of plants so called because it tends to produce rust/orange coloured spores on plant leaves. E.g. Leek rust.
Gardening Terminology – S
Sands are one of the coarser constituents of the soil and those soils with more than 85% of material classified as sand are referred to as sandy soils.
The size of sand in soil ranges from 0.05 – 2.00 mm in diameter.
Sand is derived from rocks that have been broken down by rain, frost, wind etc. Sands composition depends on the rock from which it is derived but is largely silica-based. However, the second most common constituent of sand is calcium carbonate, which is typical of those sands derived from corals and seashells.
Saprophytic plants derive their nutrients from dead organic matter. Fungi, including cultivated mushrooms, are typical saprophytes.
Saprophytes are important to gardeners even when they are not visible. For example mycorrhizal soil fungi break down organic matter in the soil and lead to the release of plant nutrients.
Seed compost is produced for the sole purpose of germinating and growing on seedlings. It is usually open and free draining with a pH around neutral. Other than lower levels of nutrients the compost can contain peat or be peat-free.
The plant when it emerges from the seed and for a few days thereafter. Typically seedlings consist of three main parts: the embryonic root or radicle, the embryonic shoot/stem (hypocotyl), and the seed leaves (cotyledons).
Plants that produce their own pollen and can therefore pollinate themselves are self-fertile. Eg Victoria plum
Sepals, of which each flower has many, together form the Calyx of the flower. Like the petals, they are modified leaves, but sepals sit below the petals in the open flower. They form a cover over the petals when the flower is closed and are largely what is seen as the flower bud.
Silt, an important soil constituent, is the granular non-organic material that is sized between sand and clay.
Soil is a complex mixture of rock particles ranging in size from sand to clay; minerals, stones, organic matter, chalk, peat, gases, liquids, humus, soil organisms and empty spaces, that is found on the surface of the planet.
Soil is normally recognised as having four distinct functions:-
- A growing medium for plants of all descriptions.
- A medium which retains gases, such as CO2, in various forms and hence modifies the earth’s atmosphere.
- A habitat for soil organisms
- The filtration, purification, storage and supply of water.
The treatment of soil to render it sterile. I.e. free of pests, diseases and weeds. It can be accomplished by heat where greenhouses are steam sterilised. On a smaller scale, small units of spoil can be heat sterilised in a microwave. Chemical sterilisation is also possible and previously chemicals such as the highly toxic methyl bromide gas were used to fumigate soils. This is now illegal.
A measure of the proportion of sand, silt and clay in a soil. If moist soil is rubbed between the finger and thumb clay solid will feel silking whilst sandy solid feel gritty. To determine the soil type it is necessary to actually measure the relative percentage of each component.
Soil is generally classified into loams, clays, silts, sands, peats and chalks.
The plant family that includes potatoes, tomatoes, peppers, chillis, aubergine, Cape gooseberries, tobacco and a host of other plants. The edible plants will be familiar to many people but the family also includes many weed species, some poisonous, such as Black Nightshade.
A type of moss that, when it dies and decomposes, produces peat moss.
The equivalent of a seed produced by non-flowering plants such as ferns.
Square Foot Gardening
Square foot gardening is a method of growing devised by retired engineer Mel Barlow. The idea is that growing beds are divided into squares, each measuring one foot by one foot, in which crops are grown. The recommendation is that beds are 4 foot by 4 foot square or multiples of this eg. 8×4, 12×4 etc.
Square foot gardening is claimed to be very efficient n that it allows each square to be cropped differently and hence rotated as it matures, that water usage is much lower and that gardening takes significantly less time.
Personally I believe it to be an expensive system that is environmentally unfriendly as it is recommended that moss peat, vermiculite and blended compost are used. The use of peat is not consistent with environmental stewardship and the production of vermculatite uses fossils fuels produces vast quatities of CO2.
Read my full article on Square Foot Gardening here.
The use of long stakes to support plants.
The male part of the flower. The part that produces pollen.
The Stigma is the part of the flower that receives the pollen and is where it germinates. It is often sticky so it can retain the pollen. Pollen is often desiccated when it is transferred, so the stigma often rehydrates the pollen before it germinates.
Stigma come in various shapes and forms. Most are relatively small but some, like the maize stigma, is a long silky tassel that is highly visible.
The placing of seed in layers or strata in a sand bed to preserve them or to encourage germination. In the case of cold stratification, low temperatures are used to improve germination.
Stolon are horizontal plant stems that are used as a reproductive structure. They grow along the soil surface and develop (adventitious) roots and small plants at intervals along the stem. This is typically seen in strawberry “runners” as strawberries are a stoloniferous plant.
Stolons and rhizomes are sometimes confused.
Elymus repens (colloquially couchgrass, twitch etc) is a pernicious grass weed that reproduces via rhizomes. Rhizomes are similar to stolons but can grow horizontally underground or on the surface. Technically they are underground stems and come from axillary buds.
To most gardeners the difference between a stolen and rhizome is an obscure botanical technicality!
The style in a flower connects the ovary to stigma. It is usually a short or long tube but is sometimes absent n which case the stigma is referred to as being sessile.
An offshoot that emanates from a root.
Planting crops in succession so that they can be harvested over a long period in succession.
Not natural, man-made.
Something that affects a whole system such as the whole plant. For example, systemic pesticides affect and are found in, the whole plant.
Gardening Terminology – T
An astringent substance in plants such as grapes, some tree barks and leaves. It is also found in chocolate, cloves, tarragon, vanilla, tea, beer, and is used in the tanning process
The main root in a non-fibrous rooted plant. Typically it is the longest root, goes deep into the soil, and is the source of the lateral roots.
Tender plants are susceptible to cold weather and die if frosted or if the temperature drops too low for them.
A specialised leaf, petiole or stem that is thread-like and used to support climbing plants by climbing around suitable supports by means of Thigmotropism.
Most organisms have two sets of chromosomes, where they have four they are said to be tetraploid. This usually means much larger plants which can be an advantage or problem! Some early wheat, for example, Wild Emmer & Emmer wheat, are both tetraploid and this led to much higher yields which helped establish agriculture and the development of humans.
Many cereal crops are polyploid, meaning they have three or more sets of chromosomes.
Some potatoes and leeks are tetraploid.
The term previously used in botany to describe the receptacle.
The layer of material near the soil surface that has not decomposed and can harbour pathogens. It is common on lawns and inhibits growth where it prevents water percolations and can limit gaseous exchange between the air and soil air.
Thermotropism is a plant’s growth response to temperature. The example commonly quoted is the curling of Rhododendron leaves during cold temperatures. I’ve also observed this in winter grown lettuce in unheated greenhouses. In very cold weather lettuce show some leaf curling, a degree of leaf wrinkling uncharacteristic of the variety and also “hug the ground”, as if for warmth or shelter.
Thigmotropism is the process where climbing and other plants detect and respond to solid objects. Climbing plants and vines use tendrils to twine around solid objects to gain support for the plant. This is positive thigmotropism.
A similar process takes place where plants use adhesive pads to adhere to objects such as walls. Eg Parthenocissus spp.
Negative thigmotropism is demonstrated where plant roots grow around solid objects in the soil as they grow under the influence of geotropism.
The practice whereby seedlings are removed from a row or area to ensure the remaining plants can grow without undue competition for light, water and nutrients.
A term used in describing the growth characteristics of grasses. A tiller is a shoot or stalk that grows from the crown or base of the plant.
A tool, device to piece of equipment used to till (cultivate) the soil. A cultivator.
A word to describe the condition of tilled soil. Eg the tilth was lumpy, the tilth is wet and sticky.
See also friable and from.
The gardening art form where perennial plants are pruned into predefined shapes. In its simplest form, a hedge could be said to be a form of topiary. In its more accepted definition, we are talking about European parterres and terraces as found in formal rigidity of Versailles. However, a large garden isn’t needed and ordinary people with small gardens have clipped box hedges into superb shapes in country gardens for generations.
topiary has also been practised internationally in countries such a China and Japan where the rigour of Versailles is often surpassed. Japanese topiary is equally as formal but appears more relaxed and natural with cloud pruning of trees in Japanese Zen Gardens. A subset of this art form is Karikomi, where gentle curves are cut into hedges to resemble clouds. Cloud hedges were later copied into the English landscape and can be seen in some English landscape gardens.
The most severe, and perhaps formal form of topiary is bonsai.
In pedology (a branch of coil science) the topsoil is literally that, the soil at the top of the soil profile. Ocassopnaly the topsoil is buried by poor cultivation techniques but it should be the top layer.
The ideal topsoil is deep, at least 6 inches and preferably a foot or more. Topsoils contain the bulk of the organic matter in soil and are derived from parent rocks below the topsoil or it may have been deposited by floods or other mechanical action. The topsoil also contains the bulk of the soils microorganisms and is where most biological activity is to be found. They, therefore, need to be well aerated if the microorganisms are to thrive.
Plant nutrients that are required in relatively small amounts compared with the major elements. E.g. Boron, copper, zinc, manganese.
To grow and survive plants rely on water moving from roots to the other parts of the plant. Transpiration is the process of water movement and subsequent evaporation of water from the plant parts designed for this.
Only a small amount of water taken up by the roots is used for metabolism and growth, the remainder is voided through the stomata and evaporates.
To move a plant from one place to another. E.g. lettuce maybe be grown in plugs, modules or pots then transplanted into the garden. Or brassicas and leeks maybe be grown in a seed bed and transplanted into their final growing positions in growing beds,
A form of irrigation often found in horticulture. A simple example would be soaker hoses. When growing commercially I used drip irrigation, which provided a gentle trickle of water to tomato, pepper and cucumber plants via a drip nozzle. In orchards, a similar form of drip or trickle irrigation is often used to irrigate trees.
As with most forms of irrigation, trickle can be controlled by a computer that may be programmed to irrigated at preset times or when a moisture meter determines need. The computer may also adjust the amount of water given based on the amount of sunlight or other factors.
The response of a plant to an external stimulus.
After the cotyledons have developed w get the first true leaves. This means they are often the second pair of leaves that develop on a seedling. They are usually a different shape to the seed leaves.
A storage organ found in many plant species. Eg the potato is an underground tuber used as a means of asexual reproduction. In the case of the potato, the tuber is a stem tuber (not root as many suppose). Some tubers are derived from modified lateral roots eg dahlias and sweet potatoes.
Gardening Terminology – U
A botanical word meaning a cluster of flowers where the stalks spring from a common centre, are of similar length and result in a flat or slightly convex surface. An example would be the carrot flower.
Gardening Terminology – V
Plant leaves that are edged or patterned with colours are said to be variegated. Eg Euonymus fortune “Silver Queen”, named after plant hunter Robert Fortune, is a variegated Euonymus. Other variegated plant examples include Welgelias, Ilex, Ivy, Hostas, Begonias, Agave and Miscanthus.
A subgroup of a plant species. Eg Prunus nipponica var. kurilensis ‘Brillant’. Kurilensis is the variety.
NB varieties occur naturally in the wild whilst cultivars occur as a result of breeding or mutation. Cultivars are written with a capital letter and/or put into italics.
An organism capable of transmitting an infectious agent.
Vermiculite is produced by heating mica until it expands. Heating produces a light spongy material that is able to hold air and water in composts. The process of mining and manufacture is energy-intensive and produces large volumes of CO2.
Plants often need a period of cold to initiate growth or flowering. Frosts are important for this process which s called vernalisation.
See Also Stratification
Vertical growing is where the plants grow, or are arranged, vertically.
At a basic level, this includes cordon and espalier fruit such as tomatoes, cucumbers and runner beans to apples and pears.
Vertical growing also includes where a series of pots or containers are stacked above one another in a vertical plane. Eg using pot holders affixed to a wall.
Vertical growing can also include green walls etc. This is usually achieved using hydroponics.
A genus of fungi, some of which cause verticillium wilt in plants.
Plant viruses cause a wide range of problems. It has been argued for a long time that a virus is not actually alive as it is only able to reproduce within a host (the plant in this case).
The production of toxic gasses by plant leaves to inhibit nearby competitors.
Gardening Terminology – W
The Wardian case is named after Victorian plant hunter Dr Nathaniel Ward who wanted a container in which he could transport his specimens back to England. Plants in pots travelling in the holds of ships died due to a lack of light and, on deck, they suffered salt spray and adverse weather conditions.
So in around 1829 Ward designed an airtight glass case in which plants could travel. It’s a similar concept to bottle gardens or terrariums. There is some evidence that similar containers had been in use prior to Wards invention!
Waterlogged soils are those that are completely saturated with water. They, therefore,
lack air and most plants will die in a few days without air. Waterlogging can be temporary or permanent.
A plant growing in the wrong place. Eg a potato growing in a lawn is as much as a weed as a thistle in the lawn!
Mulch made of chipped wood. Used also as a growing medium. Some wood contains growth inhibitors so should be avoided eg. juglone from some walnut species.
Plants are said to go woody when the stem starts to harden and grow bark.
Gardening Terminology – X
A chemical found in plants that causes yellow colouration of leaves and stems. It is usually masked by chlorophyll but becomes apparent when the plant is shielded from sunlight and the production of chlorophyll is stopped. Eg. if you cover grass with a material that prevents the grass getting any sunlight it will go yellow.
Xeriscaping is a water conservation process where landscapes are designed that use minimal or no irrigation. The landscapes and plants in it survive on natural rainfall. It’s, therefore, more appropriate to landscaped amenity and ornamental gardens as many veg need watering when the crop is getting established or bulking up.
That part of the plant’s vascular system that transports water and any dissolved substances.
Gardening Terminology – Y
Yellowing of leaves is often indicative of a number of fungal and viral problems. Eg. Fusarium Patch in lawns and Fusarium Wilt in tomatoes.
Gardening Terminology – Z
The dispersal of plant seeds and fruit by animals such as ants, bats, birds, monkeys etc. This is viable seeds that become attached to fur, feathers etc, or in the digestive system etc.
Examples include cherry stones spread by birds and even tomatoes spread by humans!
Zygomorphic flowers are where there is one plane of symmetry meaning it’s bilaterally symmetrical. Ie symmetrical side to side such as peas, salvias and penstemons rather than being like a daisy where a line of symmetry can be drawn through the centre of the flower at any point.
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