How to get the best results from your free seeds
Whether you've sown a million seeds before, or none, Sally Nex is here to help you improve your germination rates to get more from your free seeds. Next month, she'll share advice on caring for seedlings
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If it’s thrilling, edge-of-the-seat wonder you want – just sow a seed and then watch as the first tender leaf nudges up into the light. It’s pure magic, and one of the true joys of gardening. It’s also by far the most affordable way to fill your garden with flowers and home-grown veg – even more so when your seeds come free with your copy of Gardeners' World mag.
If you’ve found sowing from seed challenging, this is the guide you need to create exactly the right conditions to kick-start your seeds into life. In part two we look at what happens next, and how to keep your baby seedlings growing on strongly.
Sowing under cover
Most seed is safer sown under cover. That means sowing them into pots, seed trays or modules of peat-free seed compost which you then keep in an unheated greenhouse or on a bright, sunny kitchen windowsill till they’ve germinated. This is a great technique for protecting slug-caviar seeds like sunflowers or lettuce which would otherwise be devoured as soon as they pop up. Under cover it’s also easier to create perfect conditions for germination.
What to sow into
Which pot you choose for sowing largely depends on how many plants you want to raise. When you need dozens of plants – lettuces, perhaps, or flowers like cosmos – scatter seed over a seed tray filled with seed compost. But you’ll rarely need more than a dozen large, generous plants like tomatoes, brassicas, sunflowers or chard – so a pinch of seed is plenty, sprinkled over the compost in a 10cm clay pot. Newspaper pots make great modules for seedlings like coriander which don’t like root disturbance. Sow large seeds, like beans or sunflowers, singly into cardboard loo roll inners.
Do I need a propagator?
Most seeds germinate at 18-21C. A heated propagator helps guarantee this but it’s not a must-have as happily this is also about the same temperature as a room indoors. If you are managing without, though, bring seed trays on windowsills further into the room on cold nights so they don’t get a sudden chill.
Propagators with a thermostatic control allow you to set the temperature accurately – though you’ll still need to remove the lid on sunny days to stop it overheating. Remember too that seedlings need good light levels as well as warmth to thrive, and sunlight is in short supply before mid spring. Generally speaking, wait till at least March before you sow, even indoors.
Seed compost explained
Large, robust seeds like sunflowers, beans, sweetcorn and peas manage perfectly well in ordinary peat-free multipurpose compost. But for small seeds, a specialist seed compost is essential. They’re fine textured, allowing seedlings to push up easily, and low-nutrient: over-rich compost can damage delicate seedlings.
Most leading peat-free brands now offer seed composts: if you don’t get on with the brand you’re using, try another as different blends of peat-free ingredients can perform quite differently. Or simply make your own by mixing two-year-old leafmould with equal quantities of garden soil. Sieve finely and be prepared to nip out any weed seedlings as they emerge.
Sowing outdoors
Test your soil with the back of your hand, and once it stops feeling chilly – usually April to May, depending on where you live – seeds can go straight into the ground where they’re to grow.
Weed and rake the area first to make sure there are no stones or clods to get in the way of emerging seedlings. Sow veg in rows, watering the bottom of the drill beforehand so you’re sowing onto damp soil. Cover lightly with more soil, burying seeds only to the point where you can’t see them any more (if you sow too deep, seedlings run out of steam before they reach the surface). Or create natural looking drifts of flowers like nigella or eschscholzia through mixed flower beds by scattering seed randomly across well-raked bare soil in the gaps. Gently rake again to work seed into the surface of the soil and they’ll be up in a couple of weeks.
Top tricks for getting better germination rates
- Always check sow-by dates on seed packets – after this date germination is less certain
- Pop sheet glass, cloches or clear polythene on veg beds for a fortnight to pre-warm soil
- After scattering seed, use a pencil to space them 1-2cm apart to prevent overcrowding
- Store seeds somewhere cool and dry to keep them in the best condition for germination
- Cover just-sown seed trays with a sheet of glass so they don’t dry out too quickly
Pre-germinating seeds
For guaranteed seedlings, pre-germinate larger seeds first. Lay parsnip, squash or sunflower seeds in a single layer across damp kitchen towel in a takeaway tray with a lid and pop into a warm airing cupboard. Check daily, keeping the paper moist until tiny shoots appear. Remove each seed as soon as it’s sprouted with tweezers and pot up straight away.