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Seed Germination:
From Little Things

The way different varieties emerge from a seed depends on their size and shape.

Growing your own food from such a tiny seed can be really empowering, but many people find it challenging. Successful germination is about providing the right environment for particular seeds to flourish. And once you get the hang of it, a whole world of new varieties will open up to you.

There are so many reasons why growing your own plants from seed is better than commercially available seedlings. For the small cost of a seed packet, you can grow a huge amount of food. The number of varieties which become available to you increases enormously and, if you go one step further and save the seed from plants which have acclimatised to your individual conditions, you’ll produce plants which are healthier and more robust than anything you can buy off the shelf.

Stored Energy

Spring is hands-down the most exciting season because one of the most satisfying things we can do as gardeners is sow a tiny seed and watch it burst out of the soil. As the soil begins to warm and days start to lengthen, now is the best time of year to plan and start off your summer vegetables. Generally speaking, it’ll take you about a month to grow healthy and strong seedlings which are ready to plant out into your garden.

Seeds are amazing. Held inside their tiny package is everything a young seedling needs to germinate, put down its first roots and produce its first leaves. When a seed is exposed to the right conditions, water and oxygen are taken in through the seed coating and the germination process begins. At that point, the embryo’s cells start to enlarge which breaks open the seed allowing the root – or radicle – to emerge first. Once the root has found what it needs, it’s quickly followed by the shoot – or plumule – which contains the plant’s stem and first leaves.

These first leaves are called cotyledons and are preformed within the seed. They contain enough nutrition for the plant’s first week of life, but after that it will require additional nutrients to develop into a healthy seedling. And that’s where we come in.

Homemade seed pots are free, easy to make and can be planted in the ground. Photo by Julie Bennett


Ensuring your seedlings have enough nutrition is very important. Confusingly, starting your seeds off in pure seed-raising mix is actually not ideal. Off-the-shelf seedraising mix rarely contains enough nutrients to see a hungry seedling through to when it’s ready to go in the ground. A better alternative is sowing seeds into a blend of good-quality potting mix and organic matter which has been sieved to remove any large pieces (see breakout). Using sieved potting mix on its own is fine, but adding an equal amount of organic matter will give your young and hungry seedlings a fantastic boost of nutrients.

Using seed-raising mix to lightly cover small seeds which have been spread over the blend is a better option because it is fine enough to allow the seedlings to emerge. That way, the roots will be able to access the nutrients in the potting mix to grow the plant well into its ‘true’ or adult-leaf stage. Watering your young seedlings with a weak seaweed or worm-wee solution will also help strengthen them.

Many garden centres will advise the addition of growing mediums like perlite or horticultural vermiculite but, unless you’re raising or propagating some particularly fussy plants, they’re not a necessary addition for raising vegetable seeds.

All brassicas’ cotyledons are shaped like a B. Photo by Linda Hampton Photography

Getting Started

One of the most common mistakes people make when starting off seed is planting it too deep. A good rule of thumb is to cover your seeds with the same amount of soil as they are in size. The smaller the seed, the less coverage it will need.

Planting a seed too deeply forces it to use all of its stored energy before the plumule reaches the surface. Another common mistake is not watering it well or often enough. Allowing a seed to dry out will mean there’s not enough moisture to initialise the germination process or to keep it growing.

The temperature of the soil also plays a major role in telling the seed it’s time to wake up. Most vegetable seeds will require a soil temperature of over 15 ºC to germinate, so placing your seed trays and seedlings somewhere warm and sunny like a greenhouse or seed-raising box (see page 80) is ideal. People wanting to get a particularly early jump on spring could invest in a heat mat on which seedling trays can be placed, and which are specifically designed to cope with the regular watering seedlings require. If you don’t have access to any of the above, a sunny internal windowsill will do the trick.

Most vegetable seed, but not all, will germinate between seven and ten days if the conditions are right. Others, like radishes, can be up within three days. In any case, patience – and water – is key.

Containers And Trays

There are many commercially available options, but there’s likely to be many useful vessels lurking in your cupboard which are perfect for seed raising. You can even make your own using newspaper which, while slightly more time-consuming, has the benefit of being able to be planted directly into the ground without disturbing the roots. As long as the container has decent drainage holes, you’ll be able to raise seeds in it. Used seedling or fruit punnets (the ones with lids act like a mini greenhouse) and even old egg cartons are all suitable for seed raising.

Make sure containers are washed and well dried first. This is especially important if the vessel has previously held soil as any pathogens or diseases will transfer to your fresh mix. Fill the container three-quarters full with your sieved mix and tamp it down gently. Place your seeds on top, ensuring each seed is about two centimetres apart, before covering lightly with seed-raising mix and gently watering. Don’t worry too much if they seem too close, not all seeds will germinate and you can thin them out to the strongest plants once they’re up. Similarly, if you’re planting into pod-type seed trays, you can sow two or three seeds per cell and thin out to the healthiest as they pop up. If you are sowing alliums – onions, leeks, spring onions, etc. – you’ll get best results if you sow them in a row and cover with seed-raising mix or sand.

Alliums are best seeded in rows. Photo by Linda Hampton Photography

Direct Seeding

Some seeds prefer to be sown directly into the soil where you want them to grow instead of being raised in containers and transplanted. As a general rule, root vegetables like carrots, parsnips, radishes and turnips don’t like to be transplanted as they have a delicate tap root. If you have ever planted out a punnet of carrot or parsnip seedlings into your garden, only to find a tangled mess of stubby roots at the time of harvest, it’s not that you can’t grow them in your soil, these type of vegetables will never transplant well and really shouldn’t be sold as seedlings.

To sow carrots and parsnips direct in the soil, make a small furrow and sprinkle a fine line of seed before lightly covering with seed-raising mix, fine soil or sand. Water in gently and be sure to keep them moist – but not wet – with a daily light watering to have the best chance of successful germination.

Birds will love to eat your newly sown seed and will also enjoy digging around young plants for worms, so some form of netting or wire covering will keep seeds safe until they’re big enough to hold their own in the garden.

Larger seeds like broad beans, peas, climbing and bush beans are also good varieties which prefer to be directly sown. These need to be sown as deep as they are tall; usually to your first finger joint is a reliable guide. Despite having relatively large seeds, cucurbits like pumpkins, zucchinis, cucumbers and melons will do best if two individual seeds are started off in a small pot and you thin out to the strongest plant after germination.

Planting Out

Knowing when to transplant your seedlings into the garden is important. If it happens when they’re too young, they’ll go into shock and won’t survive. And if you wait too long, their health will have deteriorated after depleting all the nutrients from the mix.

A seedling will generally tell you when it’s ready to be planted out in the garden when it has three or four of its ‘true’ or adult leaves growing above its cotyledons. It’s also a good idea to harden off your seedlings before moving them from the warm seed-raising environment out to the garden. Place the trays in a protected spot outside for a few days and allow them to acclimatise to life outdoors. Watering your plants in with a seaweed solution after planting will help reduce transplant shock.

Learn From It

Photo by Linda Hampton Photography

Part of the journey of raising your own seed is sometimes failing. You can’t really call yourself a gardener if you don’t kill a few plants and some of us have killed way more than others! Sometimes it won’t matter how well you tend to them, there’s some seed that just won’t germinate. If seed is over two years old, has been stored incorrectly, sown too deeply, watered too much or allowed to dry out after planting, your seeds probably won’t germinate. But have a think what may have gone wrong and try again. And know that when you are growing something from seed, you are truly taking control of the food you eat.

DIY seed-raising mix


2 parts sifted potting mix

2 parts sifted compost

1 part worm castings

1 part seed-raising mix or sand


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