Seed saving and exchange

What seed saving is for

Every saved seed is a small decision. Whoever lets the best bean plants ripen and sows their seed again next year chooses, harvest by harvest, the plants that cope with this soil, this heat and this rhythm of rain. After a few generations the variety belongs to the place. The seed cycle describes how this works in nature and where modern farming breaks the chain with bought seed. This page is about the handwork that closes it again: choosing, ripening, cleaning, drying, storing, testing and sharing.

Seed saving begins with the right variety. Only open-pollinated varieties grow true from their own seed; the seed of F1 hybrids splits into a mixed offspring, as the seed cycle page explains. Old local varieties, often called heirlooms or landraces, are the natural starting point, because they have already been shaped by gardeners for generations.

Easy and demanding plants

Plants differ in how they are pollinated, and this decides how much care seed saving takes.

• Mostly self-pollinating: garden beans, peas, lettuce and most tomatoes. They seldom cross with neighbouring varieties and need little distance. Seed-saving guides commonly name about ten plants as enough to keep a variety healthy.
• Cross-pollinating: squash and pumpkins, maize, cabbage and its relatives, beets, carrots and onions. Insects or wind carry pollen between varieties, so they need distance, flowering at different times, bags over the flowers or hand pollination. They also need more plants; for maize, which quickly suffers from inbreeding, guides and extension services often recommend around 200.
• Biennials: carrots, beets, cabbages and onions flower only in their second year and must be kept alive through the winter.

Broad beans sit in between: bees visit them, and they cross more often than garden beans.

Step by step

1. Choose the plants. Mark several healthy, typical plants early in the season. Pull off-types before they flower, so they do not pollinate the rest. Do not save seed from diseased plants, because some diseases travel with the seed.
2. Let the seed ripen. Dry seed stays on the plant until pods turn brown and rattle. Fleshy fruits are left past eating ripeness: cucumbers turn yellow, aubergines dull and hard.
3. Harvest and clean. Dry seed is threshed in a sack or by hand and winnowed in a light breeze. Wet seed is scooped out and washed; tomato seed is first left to ferment in a jar for a day or two, which removes its gel coat.
4. Dry. Spread the seed in a thin layer on a screen, cloth or plate, in shade and moving air, and stir it daily. Hot sun and ovens damage it; a common limit is about 35 degrees Celsius. Large seeds are dry when they snap instead of bending.
5. Store. The seed physiologist James Harrington gave a rule of thumb that is still taught: within the usual ranges, each percentage point less moisture in the seed and each five degrees Celsius cooler roughly doubles its storage life. Sealed glass jars in a cool, dark place serve well. Cold storage only helps if the seed is fully dry, because fridges are humid.
6. Label. Variety, year, place and number of parent plants. Unlabelled seed is soon worthless.
7. Test before sowing. Put ten seeds on damp paper in a closed box and count how many germinate within a week or two. Seven out of ten means 70 percent, and the sowing can be adjusted.

Exchange: keeping varieties alive

A seed jar on a shelf does not keep a variety alive for ever. Seed ages, and only sowing renews it. That is why sharing is part of saving. At a seed swap, gardeners bring their surplus and take other varieties home; a seed library lends seed and asks for some of the new harvest back.

The best known network began with two packets of seed. In 1975 Diane Ott Whealy and Kent Whealy founded Seed Savers Exchange in the United States, starting from a morning glory and a tomato that her grandfather's parents had brought from Bavaria when they emigrated in 1884. In Italy, Rete Semi Rurali brings together groups that conserve and develop farm diversity. At the far end of the chain stands the Svalbard Global Seed Vault in Norway, which keeps safety duplicates from gene banks around the world, more than 1.4 million seed samples.

An example from Sardinia

In 2011, researchers of the Sardinian germplasm bank at the University of Cagliari collected and stored seed from the ancient wild olive of sa Tanca Manna near Cuglieri, in Montiferru. In the great fire of 2021 the old tree was badly damaged. In December 2023, children of the Cuglieri school planted seedlings raised from the saved seed at the original site and in their schoolyard. The seedlings are not copies of the old tree, since every seed is a new combination, but they carry its lineage on. Seed saving is insurance against loss, and at the same time the start of something new.

Common mistakes

• Too few plants. Seed from one or two plants narrows a variety, especially in plants that cross.
• Ignoring crossing. Two squash varieties side by side give surprising, often disappointing offspring.
• Damp seed. Seed that is not fully dry goes mouldy in a jar, and plastic bags in a warm room shorten its life.
• Saving without sowing. A collection lives by being grown. Renew each variety every few years.
• No labels. A jar of nameless beans is a loss.

Further in the TerraWiki

• The seed cycle shows how plants sow themselves and where the chain breaks.
• Use and value diversity is the principle behind keeping many varieties, and polyculture grows them side by side.
• Bees and pollinators carry the pollen without which many crops set no seed.
• Invisible structures explains how swaps, libraries and networks work as social structures.
• Climate-adapted trees and millennial olive trees show why the seed of well-adapted mother plants is worth keeping.

On Sa Medada

Sa Medada lies on a slope in Jerzu, on the east side of Sardinia, with a dry season from about May to September. Among the plants in the ground are annual seed crops such as the fava bean and the Bambara groundnut, whose seed can be harvested and sown again. Whether and how Project Eden will save its own seed is still open.