Every other page in this domain assumes you can obtain seed. That assumption holds while there are shops and it is the first thing to break in the scenario this app is written for, because seed is annual, it is imported, and a household that cannot get more has one growing season left.
Saving it is genuinely easy for some crops and genuinely difficult for others, and knowing which is which is most of the skill.
Why it matters more than it looks
- It is the difference between one season and many. Stored food runs out. A garden that can reproduce its own seed does not.
- It selects for your conditions. Seed saved from the plants that did best in your soil, your aspect and your weather, year after year, becomes better suited to your garden than anything bought.
- It costs nothing and it takes very little time for the easy crops.
- It is a thing to trade. Seed is light, valuable, easy to share, and swapping it is how varieties survive. See community and mutual aid.
Saving seed for your own use is lawful. The restrictions on selling and marketing seed varieties do not affect a household saving and swapping its own.
F1 hybrids
The first thing to check on the packet.
F1 hybrid means the seed is the first generation cross of two carefully maintained parent lines. The plants are uniform and often vigorous, which is why they are sold.
Seed saved from an F1 does not come true. The next generation segregates into a mixture of plants, most of them worse than the parent, and there is no way round it. The uniformity was in the cross, not in the seed.
So for seed saving you want open-pollinated varieties, which may be labelled OP, heritage or heirloom. They come true, generation after generation.
Buy open-pollinated seed deliberately, now, while you can choose. A cupboard full of F1 packets is a cupboard with one season in it.
Keep some F1s if you like them. Nothing is wrong with growing them; just do not count them as a seed supply.
Start with the easy four
These four pollinate themselves before the flower opens, so they need almost no isolation and a single plant can give you seed. Between them they cover protein, a fruiting crop and a salad, which is a reasonable start.
Peas and beans: leave some pods on the plant until they are brown, dry and rattle. Bring them in if the weather turns wet, and finish drying indoors. Shell, dry further, store.
Tomatoes: scoop the seeds and their gel into a jar with a little water and leave for two to four days until a scum forms. That fermentation breaks down the germination-inhibiting coating around the seed and kills some seed-borne disease. Then rinse thoroughly in a sieve, spread on a plate or paper, and dry completely.
Lettuce: let one good plant bolt, flower and go to fluffy seed heads. Shake or rub them into a bag. Expect chaff, which does not matter.
Runner beans cross readily between varieties, so grow one variety, or keep them well apart, if you want them true.
The harder ones and why
Cross-pollination is the big one. All the brassicas will cross with each other, so kale, cabbage, broccoli, sprouts, swede and turnip can all interbreed and give you something nobody wants. Squash crosses within its species. Sweetcorn crosses over long distances on the wind.
Isolation distances are large, often hundreds of metres, which most gardens cannot provide. The alternatives are hand pollination with bagged flowers, growing one variety of each family, or accepting the cross.
Biennials take two years. A carrot grown this year must overwinter and flower next year before it sets seed, occupying ground for a second season. That is a real cost in a small garden.
Population size matters. Saving from two or three plants of an outbreeding crop produces inbreeding depression within a few generations: weaker, less vigorous plants. Twenty plants is a rough working minimum for brassicas and carrots, and more is better.
The honest advice: do the easy four well, and buy the rest while you can. If you want to go further, pick one difficult crop and learn it properly rather than attempting everything.
Choosing what to save from
The part that decides whether saved seed gets better or worse each year.
- Save from the best plants, not the leftovers. The instinct is to eat the good ones and save seed from the runt. That selects backwards, every year.
- Mark good plants early, with a stick or a ribbon, before harvest tempts you.
- Select for what you actually want: flavour, yield, earliness, disease resistance, standing through winter, not bolting.
- Never save from a diseased plant, or from one that bolted early.
- Save from several plants, not one, and mix the seed. Even for self-pollinators this keeps some diversity.
- Keep the true type. Rogue out anything that does not look like the variety before it flowers.
Wet seed and dry seed
Dry seed is inside a pod, husk or head that dries on the plant: peas, beans, lettuce, brassicas, onions, carrots, herbs.
- Leave it on the plant as long as the weather allows.
- Cut whole heads or pods into a paper bag when brown and nearly dry.
- Finish drying indoors, somewhere airy.
- Thresh by rubbing or crushing, then winnow: pour from one container to another in a light breeze or in front of a fan, and the chaff blows away.
Wet seed is inside a fleshy fruit: tomato, cucumber, squash, melon.
- Let the fruit ripen fully, past eating ripe for cucumbers and squash.
- Scoop the seed out.
- Rinse the flesh off thoroughly. Tomatoes need the fermentation described above; the others just need washing.
- Dry completely and quickly, spread thin, out of direct sun.
Complete drying is the whole thing. Seed stored with any moisture in it rots or loses viability fast. It should be hard and snap rather than bend.
Drying and storing
Paper envelopes inside an airtight jar is the classic arrangement: the paper lets any residual moisture equalise, the jar keeps the damp out.
A sachet of silica gel, or a spoonful of dried rice in a twist of paper, in the jar, absorbs stray moisture.
Label everything immediately. Variety, and the year. Unlabelled seed is a lottery, and everybody who thinks they will remember is wrong.
A cool cupboard on a north wall is fine. A garden shed is not: it swings through hot and cold and damp, which is the worst combination.
The freezer works for long-term storage of thoroughly dried seed, in a sealed airtight container. Let it come back to room temperature before opening, so condensation forms on the outside of the jar rather than on the seed.
How long seed lasts
Parsnip and onion are the short ones, and they are the ones people are caught out by. Fresh seed every year for those.
Poor storage halves these numbers. Good storage extends them considerably.
Old seed is often still worth sowing, just more thickly, which is where the germination test comes in.
Testing before you rely on it
Ten minutes in January that avoids an empty bed in May.
- Count out ten seeds from the packet.
- Lay them on damp kitchen paper, roll it up or fold it, and put it in a plastic bag somewhere warm.
- Check after the normal germination period for that crop, usually one to two weeks.
- Count how many sprouted. Seven out of ten is 70% germination.
Then adjust. At 70% you sow a bit more thickly. At 30% you sow much more thickly or buy fresh. At zero you have found out in January rather than in June.
Test anything over two years old, and everything you saved yourself the first few times, so you learn whether your drying and storage are working.