Testing your seeds now will save you time, effort and waste in your garden come spring

I like to think of myself as an organised person, but if you met my seed box, you may disagree. It’s a recycled shoe box that once housed wellies, with cardboard dividing it into compartments labelled by plant family. Each section is a chaos of packets, envelopes, little jars and paper folded around seeds that have been bought, shared and saved. Not everything is labelled, some packets are empty and many of the seeds have been hanging around for too many years to still be fertile.

Seeds don’t last for ever, unfortunately. Their viability varies depending on how long they have been stored, the conditions they have been stored in and the type of seed – onion seeds, for example, are best sown within a year or two, whereas cucumber and kale seeds can be stored for about five years.  Generally speaking, a seed will last longer when it is kept in the opposite conditions to those required for germination. For most seeds, this means keeping them cool and dry.

During this quieter time of year, with the sowing season soon to come, conducting seed viability tests is a worthwhile and timely task that can help you determine whether to sow the older seeds you already have or buy new ones. It’s a relatively straightforward process.

Take the seed that you’d like to test and sprinkle a sample on a piece of dampened kitchen towel. Larger seeds – such as peas and beans – are worth soaking first. Then put your dampened seeds on a plate and pop them either into a freezer bag or a plastic container before placing them somewhere warm. If you’re testing multiple seeds at the same time, it’s essential that you’re diligent with your labelling as it’s incredibly easy to forget what’s what once you’ve left them to (hopefully) germinate.

Check your seeds every few days for signs of sprouting, making sure that the paper is kept moist but not saturated (which will cause your seeds to rot before they have a chance to emerge). After about two weeks, all the seeds that are viable ought to have germinated. You’ll want to see some seed leaf and root development.

Ideally, all the seeds will have germinated, which would make their germination rate 100%, but for older seeds it’s likely that the rate will be lower. If half of your seed sample show signs of life, they’ve got a 50% germination rate so it’s a good idea to sow twice as many seeds as you would with fresh seed to get the results that your planting plan calls for.

Sowing into a tray then pricking out the seedlings that do appear is another way to use low viability seed. Anything lower than 50% is probably not worth your effort, the compost they’d use or seed tray space they’d take up.