How do I save seeds from my own plants?

Seed saving works well for some plants and unpredictably for others. The main determinants are whether the variety is a hybrid and whether the plant self-pollinates or crosses readily with neighbours.

What you'll need

• Paper envelopes or jars
• Sieve (optional)
• Labels (optional)

Step by step

1. Check whether the variety is open-pollinated or F1.F1 hybrid seed does not come true — the offspring are variable and usually worse. Open-pollinated and heritage varieties come true and are what to save from.
2. Start with the easy self-pollinators.Tomatoes, beans, peas and lettuce mostly self-pollinate and come true reliably. They are the sensible place to begin.
3. Be careful with plants that cross readily.Squash, courgettes, brassicas and sweetcorn cross with nearby relatives, so saved seed can be unpredictable unless plants were isolated.
4. Save from the best plants, not the leftovers.The healthiest, most productive, best-flavoured plants. You are selecting, so save from what you want more of.
5. Let the seed mature fully on the plant.Beans until the pods are dry and rattling; tomatoes until fully ripe or slightly over. Seed harvested early does not germinate well.
6. Clean and dry the seed thoroughly.For tomatoes, ferment the pulp in water for a few days, then rinse and dry. For dry seed, separate from the chaff and dry for a week or two.
7. Store cool, dark, dry and airtight.Paper envelopes inside a sealed jar, in a cool cupboard or the fridge. Moisture and warmth are what destroy viability.
8. Label everything with variety and year.Viability varies: onions and parsnips barely last a year, while tomatoes and brassicas last four or five. Without a date you cannot judge.

Tips

• Test old seed by germinating ten on damp kitchen paper. If seven come up, the packet is fine; if two, sow much more thickly or replace it.
• Seed swaps are an excellent way to get open-pollinated varieties and local knowledge at the same time.
• Silica gel packets in the storage jar keep the seed dry and noticeably extend viability.

Common mistakes

• Saving seed from F1 hybrids — The offspring do not come true and are usually variable and poorer. Only open-pollinated varieties reproduce reliably from saved seed.
• Storing seed before it is fully dry — Residual moisture causes mould and destroys viability within weeks. Dry thoroughly before sealing anything.
• Not labelling with the year — Viability varies enormously by species. Without a date you cannot tell whether a packet is still worth sowing.

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