How to test seed viability

Takes just:

15 minutes

Sowing old veg seed is a bit of a gamble. It might germinate well, but it might not. Over time, seed viability decreases, and different seeds have different storage times.

To take the guesswork out of sowing old seed, do a simple viability test. It will tell you if the seed is worth sowing at all, and how much to sow. If only a small percentage of seeds germinate, you'll need to sow a greater number to ensure a decent crop.

Follow our 14-day test to check whether your old seed is worth sowing.

You will need

Old seeds

Kitchen paper




Lay a piece of damp kitchen towel on a plate, then sprinkle a sample of your old seed in individual rows to aid identification.

Cover the plate with clingfilm and keep it in a warm place indoors. Make sure the towel stays moist and check regularly for signs of germination, noting the date when shoots appear.

Germination times vary between veg, but after two weeks most viable seed should have sprouted. Count how many have germinated – if it's about half, then you've got 50 per cent viability. The lower the percentage, the more seed you'll need to sow to get a decent crop.


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