How to save tomato seeds for next year: scoop the seeds and gel from a fully ripe tomato into a jar, add a little water, and let it ferment for 2–4 days until a mouldy layer forms. Rinse the seeds clean, dry them completely for 1–2 weeks, then store them in a labelled envelope in a cool, dark, dry place. Only save seed from open-pollinated or heirloom varieties — hybrid (F1) seed will not grow true.
Which tomatoes to save seed from — and which to skip
Seed saving only works if the variety breeds true. Open-pollinated and heirloom tomatoes do; F1 hybrids do not — their seed grows into unpredictable plants that rarely match the parent.
- Save from: heirloom and open-pollinated varieties (e.g. Brandywine, Cherokee Purple, San Marzano, Roma open-pollinated types). Pick fruit from your healthiest, most productive plant.
- Do not save from: F1 hybrids (the packet or label says “F1”). Their offspring split into mixed traits.
- Pick fully ripe fruit, ideally slightly overripe — the seeds inside are mature. Save from more than one fruit, and more than one plant if you can, to keep the seed line vigorous.
- Skip fruit from diseased plants. Seed can carry some diseases, so only save from healthy plants.
The fermentation method (step by step)
Fermentation removes the gel coat around each seed — the coating that stops seeds germinating inside the fruit — and kills some seed-borne disease organisms. It is the standard method for tomatoes. The same fermentation method works for cucumbers — see our guide to how to save cucumber seeds. Zucchini seeds, by contrast, are saved dry: see how to save zucchini seeds. Beans are saved dry too: see how to save bean seeds for next year.
- Cut the tomato in half and squeeze or scoop the seeds and jelly into a clean glass jar. A few seeds per fruit is normal — use 2–3 fruits for a good batch.
- Add a little water — just enough to cover the seeds — and stir. Label the jar with the variety and date.
- Cover loosely (a cloth or loose lid) and leave at room temperature, out of direct sun.
- Stir once a day. After 2–4 days a white or grey mould layer forms on top and the mixture smells sour — that means fermentation is working. Good seeds sink to the bottom.
- Rinse well. Pour off the mouldy layer and floating pulp, add fresh water, swirl, and pour off again. Repeat until the water runs clear and only clean seeds remain.
- Dry on a non-stick surface — a ceramic plate, coffee filter or wax paper (not paper towel: seeds stick to it). Spread the seeds in a single layer.
- Dry for 1–2 weeks in a warm, airy spot out of direct sun. Seeds must be fully dry — snap a test seed; if it bends, it is still wet. Damp seed moulds in storage.
- Store in a labelled paper envelope inside a sealed jar, in a cool, dark, dry place. Add the variety, date and source plant to the label.
How long do saved tomato seeds last?
| Storage conditions | Expected viability |
|---|---|
| Cool, dark, dry (room temperature, sealed jar) | 4–5 years |
| Fridge (sealed jar with a silica gel packet) | 5–10 years |
| Warm, damp or sunny spot | 1 year or less |
Germination falls gradually, not all at once. Before sowing an older batch, run the 10-seed viability test — if under 50% sprout, sow thicker or buy fresh. See also our zone-by-zone tomato sowing guide for when to sow your saved seed.
Mistakes that ruin saved tomato seeds
| Mistake | What happens | Fix |
|---|---|---|
| Saving from an F1 hybrid | Plants don’t match the parent | Only save open-pollinated / heirloom varieties |
| Skipping fermentation | Gel coat stops germination; disease survives | Ferment 2–4 days until the mould layer forms |
| Storing seeds while damp | Mould in the envelope, dead seed | Dry 1–2 weeks until a test seed snaps |
| Drying on paper towel | Seeds stick and tear | Use a plate, coffee filter or wax paper |
| No label | Mystery seed next spring | Label variety + date before the jar stage |
| Saving from a sick plant | Disease carries over in seed | Only save from healthy plants |
Do you have to ferment? The shortcut — and why it is second best
You can skip fermentation by scooping seeds out, rinsing off the gel and drying them directly. The seeds will germinate — but the gel coat remains, germination is slower and patchier, and seed-borne disease is not reduced. Fermentation takes 2–4 days of waiting and about 10 minutes of work, and it is the method seed banks and university extensions recommend. For a variety you care about, ferment.
Frequently Asked Questions
How do I save tomato seeds for next year?
Scoop seeds and gel into a jar with a little water, ferment 2–4 days until a mould layer forms, rinse clean, dry completely for 1–2 weeks, and store in a labelled envelope in a cool, dark, dry place.
Can I save seeds from any tomato?
Only from open-pollinated or heirloom varieties. F1 hybrid seed will not grow true to the parent plant — the offspring are unpredictable. Check the packet or label for “F1”.
How long do tomato seeds last in storage?
4–5 years in a cool, dark, dry place; 5–10 years in the fridge in a sealed jar. Test older seed with the 10-seed viability test before sowing.
Do tomato seeds need fermenting?
Not strictly — rinsed and dried seed will germinate — but fermentation removes the gel coat, improves germination and reduces seed-borne disease. It is the recommended method.
Why do my saved tomato seeds stick to paper towel?
Wet seeds bond to paper towel fibres as they dry. Dry them on a ceramic plate, coffee filter or wax paper instead, spread in a single layer.
