Saving your own seed is one of the most satisfying and thrifty tasks you can perform in the home garden. It also helps preserve rare and heritage vegetable varieties, which, in these current days of homogenisation, is increasingly important.

Saving tomato seed is not at all difficult, but it does involve a little more than waiting for seed to form on a plant. Because the seeds are embedded within a gel coating, saving the seed requires that you extract the seed from the gel first. This is done by fermenting the gel off the seeds before drying and storing them. The ‘gel’ is natures own germination inhibitor, so cleaning and drying the seed in this way ensures your seed will be viable in future. Fermentation also helps to kill any potential pathogens or mould that could affect seed quality.

This technique is a great way to save the best seeds from your favourite tomato varieties, while ensuring they remain healthy for the next planting season.

Here’s a step-by-step rundown on how to save tomato seed, complete with photos.

Once your tomatoes are fully ripe, cut them open and gently scrape out all the seed.

Put the seed in a glass, then add about 2 inches of water. It should be enough that the seed is fully submerged with a bit extra to break down the gel. A clear glass is a good idea, because it allows (or reminds) you to easily keep an eye out for when to change the water.

After about 3 days, fermentation will have begun, and the water will look a little cloudy and coloured (above left). The next step is to strain and rinse the mixture. I use a miniature tea strainer due to its suitable size.

Once the seed has been rinsed, repeat the soaking process. You can see (above left) that there is still some gel present, but far less than at first. Again, soak the seed for a couple of days until the solution becomes cloudy and you can see that the gel has separated from the seed. Strain and rinse a second time.

I then put the seed and some fresh water back into the glass and swirl it around, just to triple-check that the seed looks completely clean. Pour as much water as you can out of the glass, then gently place the seed on a paper towel to dry out.

Leave the seed to fully dry out- a couple of days is ideal. For longer-term storage, decant the seed into a sterile container, labelled with the variety and date.