What Is Compost? What Is Compost Good For In the Garden?

Compost Is Recommended For Growing Many Plants, But What Is Compost? Where Does Compost Come From? How Is Compost Made? What Is Compost Used For?

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Let’s Start with What Is Compost?

The simple answer is decomposed organic matter. But not just any decomposed organic material. Compost is decomposed aerobically. That means it is decomposed with oxygen from the air being used in the process. Anaerobic decomposition is what happens in landfill and that produces methane. Aerobic decomposition doesn’t produce methane. It’s a different process.

Don’t worry about having to add the oxygen to your compost, it happens automatically provided the composite has air around it. We can add more air to the compost by turning the compost. This speeds the process and makes it happen far quicker.

The real problem I see with talking about compost is that many people do not understand the term. When I write about compost I get many comments such as people can’t afford it. It’s too expensive. It would cost far too much to cover their allotment with it. The reason for this is that they seem to regard compost as something they buy from a garden centre in a bag. And they regard it as poor quality as it’s full of rubbish .. a topic I’ve addressed elsewhere.

So let’s look at these issues next.

Where Does Compost Come From?

Some of it comes from commercial or council run green waste or recycling units. It’s often then bagged and sold in garden centres and it has a bad name for containing all sorts of rubbish in it. I believe there should be a compost standard and have written about that as well.

But the best source of compost in my experience is the stuff you can make in your own compost heap. Gardeners have been doing this for years and I’ve written about the Indore Composting process and there are videos here about making compost during the last war.

Another problem people often complain about is that they can’t make enough to cover the area of land they grow on. I understand why they say this and recommend sourcing compostable material from elsewhere. There’s plenty of cardboard, food waste, lawn mowings, coffee waste etc that people have to pay to dispose of it we don’t take it and compost it.

The downside is that it takes a bit of effort. And strangely enough the people that complain loudest seem to the the ones that say using compost on No Dig gardens is lazy gardening .. there’s a certain irony in their claims!

Composting Farmyard Manures

Traditional gardeners often swear by farmyard manure, stable manure and even rabbit droppings. Others are advocates for llama poo. There’s no accounting for taste!

I often see heat4d discussion about which of the are superior for digging in and the time of year they should be used. Some say we should heap them on the land in autumn and dig them in in spring. Others say dig them in over winter. there seems so many variations to these “rules” that many new gardener get confused.

The truth of the matter is many traditional gardeners forget the other way to do things. That is to heap the manure up and compost it. In other words, decompose it in a compost heap.

One thing is sure, most of the well rotted manure I see around gardens and allotments is far from well rotted. It needs heaping up so it generates a bit of heat that will kill off the weed seeds in it. Well composted animal manures rarely contain many seed weeds.

If more gardeners composted their animal manures we’d see far fewer complain about how it spreads weeds.

What Is Peat Free Compost?

Peat free compost is any type of compost that hasn’t had peat added to it.

What Is Peat Compost?

Peat compost is wholly or largely made from peat. The harvesting of peat is however recognised as being detrimental to the planet and climate as it releases huge amounts of carbon which increases climate warming. An increasing number of commercial growers are now peat free and have established effective ways to grow seeds and plants without the need for peat. A total ban on peat is on the way so it’s a good skill to learn now regardless of the environmental issue.

What Is Ericaceous Compost?

Ericaceous compost is designed and manufactures for growing ericaceous plants in. It is for growing calcifuges in. These are plants such as heathers, rhododendron, blueberries and camellia which need acid soils. A calcifuge is a calcium or chalk hating plant. Ericaceous beds are typically pH 4.5-6.0.

What Is Loam Based Compost?

Loam based composts are those containing loam. Loam is a soil with a good mix of clay and sand particles which makes it moisture retentive and free draining at the same time. This sounds contradictory but really means that surplus water drains out and its replaced with air, but that some loam constituents retain enough moisture to allow the plant to grow.

Loam-based composts a mix of decomposed organic matter and loam. Most composts contain very little soil or loam, so a certain amount is considered desirable in some cases. In the past a lot of research was carried out on the best mix for composts and the John Innes composts were produced to match specific needs. The John Innes Institute was named after a philanthropist of the same name and still bears his name.

Woodchip Compost

Composting woodchip takes longer than many than when produces compost from softer materials. But it’s wonderful stuff when you can produce it. I’ve several articles on woodchip if you want to read them.

What Is In Compost?

As you can see from the above it can be just decomposed organic matter or it can include additives such as peat or loam. Sometimes nutrients are added with as “straights” or as organic fertiliser. The use of fertiliser pills in a compost provides temperature regulated release of nutrients when plants need them most.

The pH of composts are generally as close to neutral as to make no difference to most plants. However ericaceous composts are made for calcifuge plants.