Seeds Are Nature’s Miracles. Perfectly packed plants, in a protective coating, waiting to grow.

Or put another way they are plant embryos bursting with potential.

A comparison of vegetable seed sizes
What Is A Seed?
A comparison of vegetable seed sizes

Of course these definitions won’t satisfy the scientists, biologists and botanist amongst us. But they do describe the miracle that is a seed.

Technically a seed is a part of a plant designed to store genetic information that has the potential, in the right conditions, to grow into a new plant. Not a plant that is exactly the same as its parents, that would be a clone, but like in humans the plant that grows from the seed contains genetic information from both parents. And like in humans if one parent is tall and one parent is short then the offspring will be a mix of the two. That’s not to say that they will be the average of the two heights, though they might be. It means the offspring will follow a strict scientific rule that means if there are hundreds or thousands of offspring a mathematical ratio will be seen in the heights.

Of course, compared with plants, humans only have a small number of offspring so we only see a small proportion of the potential. So all their kids might be tall or all short or be a mix of sizes. Some might even be much shorter than the short parent and some taller than the tallest parent. And just because they have the genetic potential to be tall doesn’t mean they will be. If undernourished they’ll never grow as tall as they could.

And so it is with plants that grow from seeds.

But of course plants, like us, aren’t just short or tall. We exhibit other traits such as eye colour, hair colour, physique etc. And plants will show different flower colour (think about how many different shades plants like roses are), the flavour of fruit (think apples, tomatoes, etc), leaf share and so much more.

Seed Shape & Appearance

Vegetable seed size comparison
What Is A Seed? 
Vegetable seed size comparison with pencil lead

Seeds come in a huge range of shapes and sizes. Some such as conkers are quite big whilst celery is dust-like. there are roughly 17,000 celery seeds to the gram. And the shape is just as varied. Some seeds are bean-shaped (which is the shape of a kidney), some are spherical, some are shaped like discs and some, such as sycamores, have wings that help them travel in the wind. And it’s not just wings that help seeds to disperse on the wind. Dandelion seeds have little parachutes that help them drift on the breeze for miles.

And where winds are erratic some seeds have developed hooks and burrs so they can hook onto the fur of animals and be spread far and wide.

Some seeds are wrapped in edible surroundings so that animals will eat them and carry them for miles before depositing them in their droppings in a site where they can grow. Examples include tomatoes, blackberries and thousands of other plants. Many will not grow unless they have been through an animals’ stomach where digestive acids remove the tough outer layer from the seed.

Other seeds are long and pointed. Plants such as dahlias and cosmos are like this.

While some seeds have rough coats others, such as conkers, have shiny smooth coats. This can be important to the plant and to humans. For example in western and central Africa, people prefer rough-coated cowpeas while in eastern and southern Africa they prefer smooth-coated cowpeas (as they do in South America). Rough coated and smooth-coated cowpeas are prepared for eating in different ways.

The largest seed in the plant kingdom is the Coco de mer seed. It’s between 40-5- cm long .. that 18 inches in imperial measure! Huge.

What Colour Are Seeds?

These three seeds are L-R Winter Density Lettuce, Vailan Lettuce and Amsterdam Forcing 3 Carrot. It’s interesting that lettuce seeds can be different colours depending on the variety.

Most seeds are brown. But some’ such as the onion family are black. While sunflowers are often stripped with several colours being quite normal.






Not All Seeds Are Seeds

A large vegetable seed: Pea
A pea seed magnified in digital micrograph. The variety is Alderman, which is a wrinkled variety.

Seed potatoes aren’t seeds! Nor is beetroot seed!

Potatoes do produce seed. It’s produced in the little green tomato like structures on top of the plant whereas what we call “seed” potatoes are in fact tubers. And the reason that potatoes produce seed in tomato-like structures is that both tomatoes and potatoes are part of the same family, the solanaceae. It’s actually the same family as Deadly Nightshade and explains why we don’t eat potato fruit .. they are very poisonous.

As for beetroot, they are actually a fruit that can contain 3-4 seeds. These can be separated into individual seeds if need be, and this is often done for sugar beet where the seed is then often coated to produce pelleted seed that will go through the farmer’s seed drill.

Poisonous Seeds

Seeds are often edible. Examples include cereals such as wheat, barley, rice, maize and rye; sunflower seeds; soya beans; peas; chickpeas; etc. But some are highly dangerous to eat.

The seed of the Castor Oil Plant contains ricin and is a highly potent toxin.

Not all seeds are as dangerous as the Castor Oil Plant seed. But if in doubt don’t eat any seeds.

How Long Do Seeds Last: Seed Longevity

Seeds are nature’s perfect genetic package and can often last for years in the soil or in packets. But much depends on the variety of plant. Some years ago I ploughed a field that had been grass for as long as anyone could remember, it certainly hadn’t been ploughed in over 50 years. Within a few months, it was awash with poppies. Wild Poppy seed can apparently last for decades in the right conditions, though garden varieties may only last a few years.

How Long Do Veg Seeds Last?

Veg seeds tend to remain viable for much shorter periods than weed seeds. It’s why weeds are so successful!

Here are a few examples.

Aubergine 4 years

Beans (broad, runner and French) 2 years

Beet 5 years

Cabbage 5 years

Carrot 3 years

Courgette/Marrow 6 years

Cucumber 7 years

Kale 4 years

Lettuce 4 years

Onion 4 years

Parsnip 1 year

Radish 4 years

Tomato 3 year

Watercress 5 years

The above are all averages and much depends on the conditions the seed is kept in. When sold, seed must meet certain germination criteria as tested in the laboratory However seed potency tails off over time so the above takes in to account meeting the germination criteria for sale. It’s not to say every seed will be non-viable after the times stated above. Some might still be OK provided you accept a lower germination percentage.

Testing seed by germinating on damp paper is a good way to ascertain seed viability.

How to Store Veg Seed

Commercially purchased seed is often packed in hermetically sealed packs and need to be kep in a cool dry place. Use by the Use By date on the pack. It’s that simple!

Home saved seed

Ensure seed is very dry before storing it.

Place in paper envelopes and label with variety and date saved

Store in a cool dry place.

I’ll be writing about harvesting home saved seed on another post.

Using Seed From Shop Bought Fruit and Veg

As I explained at the beginning your seed are going to produce plants that exhibit the characteristics of the parents. And in most cases that will be to show a range of sizes, flavours, heights, temperature requirements etc.

Commercial seed producers do however select the parents that exhibit the characteristics they want. It’s not natural selection, it’s Unnatural Selection and gives more even results where the plants are all likely to be much the same.

But when we take seed from a plant that was grown for eating there has been no effort to do this. PLUS we don’t know the parentage of the seed. Many commercial seeds are produced by carefully crossing two quite different plants to get “hybrid vigour” in the offspring. But when grown in the second year this is just a random affair.

Think of it like breeding pedigree dogs. The parents are both pedigree and the offspring will be pedigree. They will look the same.

Now think what happens when a different breed of dog gets involved. We get a mongrel. Mongrels might make delightful pets but if you expected a pedigree greyhound and it crossed with a dachshund don’t expect it to be a racing success!

Fruit and veg “mongrels” might be fun to experiment with but don’t expect to get great tasting crops .. or even any crop at all!

The problem is that mongrel seed takes up as much time and effort as good seed and I know what I want to grow in my garden, tunnel or greenhouse.