Saving Tomato Seed

Many of our customers want to know how to save their heirloom seeds, especially tomato seeds. Because heirloom plants are open-pollinated, they will come true to type, if gathered properly, when sown the next year (note: this is not true with most modern varieties). Most tomato seeds are fairly easy to save, but you need to plan for it in designing your garden plot. So, here are some guidelines to saving your own heirloom tomato seeds. Note: Potato-leaved tomato plants and currant tomatoes cross-pollinate very easily and require much greater physical distancing than regular tomatoes.

1. You should have at least 5 tomato plants of the same variety to save seeds from. Because heirlooms have a broad genetic base, you want to ensure that you’re capturing as much of that base as possible.
2. Although tomatoes are largely self-pollinating , there is a chance of some cross-pollination by wind and insects. Therefore, you need to separate your “seed” tomatoes from other varieties. If you’re saving seeds for yourself, a distance of 10- 15’ between varieties is reasonable. If you’re thinking of selling the seeds, as we do, you need to space them at least 25’ apart (we use 30’ – 50’) . In determining your spacing distance, remember that tomato plants (especially heirlooms, which are indeterminate) can spread out quite a lot during the season and plant accordingly. The best way to plant your seed tomato plants is in a cluster, versus a row. You can then harvest your seed tomatoes from the innermost part of the cluster.
3. Wait until your tomatoes are fully ripe, and then choose the fruits that most fit the description of your heirloom – in terms of shape, colour, cracking, etc. Avoid fruits from double flowers. Gather tomatoes from at least 5 plants. How many tomatoes you’ll need depends on how much seed is in the tomato and how much seed you need. Paste or sauce tomatoes, or ones described as “meaty”, tend to have fewer seeds in their cavities so you’ll need to gather more fruit. Salad types will have quite a few seeds. You really don’t need a lot of seed if you’re a home gardener, so you could pick one good tomato from each plant.
4. Tomato seeds need to ferment before drying. Wash the seed tomatoes and cut them in quarters. Place them in a good-sized container and mash them up – skin, pulp and all. Pour enough cool water over them to lightly cover them and stir the mixture up.
5. Place a cloth over the container (so that dirt, etc doesn’t get in) and set the container aside, preferably not too close to living areas as when they start to ferment they’re quite odorous.
6. Leave the container for 3-5 days, checking on it regularly. A white scum will form on the surface of the water. When the scum covers the surface, the tomato seeds are ready to be processed.
7. Skim off the scum and pour some more water into the container. Dan likes to put the whole container in our laundry tub directly under the tap and start pouring water in. Stir the mix and start siphoning off the pulp and dirty water. Keep doing this until the water in the container is clear.
8. Let the mixture sit. The good seeds will sink to the bottom. Don’t use any seeds that float.
9. Pour off the water through a fine sieve/strainer to remove any residue pulp.
10. Scoop out the seeds and spread them out onto a flat surface to dry. Don’t use newspaper or paper towel as the seeds will stick to it – a plate or baking sheet works well for us.
11. The initial drying phase has to be quick – the best way to do this is to have a fan blowing gently across the seeds for the first 24 hours, mixing occasionally. After that, leave them to continue drying, making sure that you break up clumps to prevent germination and going mouldy.
12. When seeds are dry, store them in an airtight container in the fridge. This way, they should remain viable for 3-5 years.