Interactive lesson

Vegetable seed, step by step

Interactive lesson: five rules of the seed garden, isolating varieties, fermenting tomato seed, beans and lettuce, hand-pollinating squash, and biennial crops.

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The whole lesson as text

1. Five rules

Five rules apply to every crop in the garden, from beans to carrots.

A healthy, true-to-type plant — Seed only from disease-free plants that look like the variety. Pull off-types and diseased plants before flowering.
Several plants — Seed from one plant weakens the variety. Self-pollinating crops need 5–20 plants; mix the seed from all the chosen plants.
Full ripeness — Seed ripens later than the fruit for eating. Let the fruit go overripe on the plant; melons and watermelons are the exception.
Label at once — Crop, variety, year, number of plants, a note. Unlabelled seed is lost seed.

Why: Seed carries the traits of the plant it came from. A diseased, off-type or single plant weakens the variety year after year. So you choose carefully, leave enough plants and write everything down at once.

Seed only from open-pollinated plants, never from hybrids (F1).
Dry extraction: beans, peas, lettuce, onions, carrots, cabbage, maize. Wet: tomatoes, cucumbers, squash, aubergines, melons.

2. Isolating varieties

Two varieties of the same species that flower at the same time will cross.

Self-pollinators close by — Tomatoes, beans, peas and lettuce need 3–10 m to another variety. Keep old tomato varieties 10–15 m away.
Insects and wind, far — Squash, cabbage, carrots and onions: 500–1,000 m, or hand pollination and a net. Wind carries beetroot and spinach pollen for kilometres.
A hedge between varieties — A hedge, a house or tall maize between varieties reduces the distance needed. The distances are approximate, for a family garden.
Net or cage — Put a frame covered with fleece over 3–5 pepper plants before flowering. Peppers pollinate themselves under the net too.

Why: Isolation means the flower of your variety gets pollen only from the same variety. Crossing affects only the seed, not this year's fruit. A courgette next to a pumpkin gives normal fruit, but the seed in them is no good.

Brassica seed keeps 3–5 years and carrot seed 3: save one variety this year and another next year.
Two maize varieties that flower 2–3 weeks apart won't cross.