How to test seed viability

Sowing seed that is old 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, below.

You Will Need

• Seeds
• Kitchen towel
• Plate
• Cling film

Step 1

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

Step 2

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.

Step 3

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.