Why Test Seeds Before You Sow?

There is nothing quite so deflating as nurturing a tray of compost for three weeks, only to realise that nothing is going to appear. Old seed packets lurking at the back of the shed, seeds saved from your own plants, or a bargain packet from a charity stall can all have patchy germination rates. Rather than sowing blind and hoping for the best, a simple germination check on damp kitchen paper tells you exactly what you are working with — and it costs you almost nothing but a week or two of patience.

This trick is especially useful in late winter and early spring, when windowsills and greenhouses are at a premium. If only half your parsnip seeds are viable, you can sow twice as thickly and still get a decent row. If none of them sprout, you have saved yourself the compost, the space and the disappointment.

What You Will Need

The beauty of this method is how little equipment it requires. Gather the following:

• A few seeds from the packet you want to test — around ten is a good sample size
• Kitchen paper or good-quality absorbent tissue
• A clean plate, saucer or shallow plastic container
• Cling film or a clear plastic bag
• A warm spot indoors, ideally around 18–22°C
• A pen and a sticky label or piece of tape for labelling

Avoid using recycled paper with heavy printing on it, and steer clear of anything scented or lotioned, as these can inhibit germination. Plain white kitchen roll is ideal.

How to Set Up Your Germination Test

Start by dampening a sheet of kitchen paper — moist but not dripping wet. If you can squeeze a drop of water out of it, it is too wet, and the seeds may rot rather than sprout. Lay the paper flat on your plate or container.

Space your seeds out evenly across the paper, leaving a centimetre or two between each one so their roots do not tangle and you can clearly see which have germinated. Ten seeds gives you a quick percentage: if seven sprout, you have roughly 70% viability.

Fold the paper over the seeds or lay a second damp sheet on top, then cover the whole thing with cling film or slide it into a plastic bag. This traps moisture and stops the paper drying out. Label it with the variety and the date — if you are testing several packets at once, you will be very glad you did.

Place the container somewhere warm and out of direct sunlight. Airing cupboards, boiler cupboards and the top of the fridge are classic spots. If you are testing seeds that need light to germinate, such as lettuce, leave them on the surface rather than covering them.

Checking for Signs of Life

Check your seeds every day, and re-dampen the paper if it starts to dry out. Most vegetable and flower seeds will show a tiny white root — the radicle — within seven to fourteen days. Some, like brassicas and radishes, can germinate in as little as three or four days. Others, including parsley, parsnip and many herbs, take longer and may need up to three weeks.

As soon as you see a root emerging, count that seed as viable. You do not need to wait for leaves. Once you have a clear picture, usually after a week or two, tally up how many have sprouted and work out your percentage.

• 80–100%: Excellent. Sow as normal.
• 50–79%: Still worth using. Sow more thickly than usual and thin later.
• Below 50%: Use with caution, or sow very densely and expect gaps.
• Nothing at all: The seed is dead. Bin it and buy fresh.

What to Do with the Sprouted Seeds

Do not throw your germinated seeds away. Once a seed has sprouted, it can be carefully transferred to a small pot of damp seed compost, root down and just below the surface. Handle it by the seed casing, never the delicate root, and water gently. Many of these test sprouts will grow on perfectly well into healthy seedlings, giving you a head start on the season.

Bear in mind that seeds handled this way are more fragile than those sown directly, so treat them gently and keep them warm and bright. If roots have grown long and tangled in the paper, it is usually kinder to simply compost them and sow fresh — but if you have space, there is no harm in potting them up.

Tips for Better Results

A few details make a real difference to the accuracy of your test. Keep the temperature steady, as fluctuating warmth can slow germination. Use fresh tap water rather than water that has sat around, and never let the paper dry out completely. If you are testing seed that has been stored in a hot shed or a damp garage, expect lower results — storage conditions matter as much as age.

Remember that a germination test tells you about viability, not vigour. Seeds that sprout quickly and strongly are the ones to favour. Once you know your numbers, you can plan your spring sowing with confidence, knowing exactly which packets deserve a place on the windowsill and which belong in the bin.