Harvest seed only when it is fully mature, which usually means later than the crop is eaten: dry-seeded plants are cut when pods and heads turn brown and dry, and wet-seeded fruit is taken ripe or overripe before the seed is washed out. Immature seed germinates poorly or gives weak seedlings, but waiting too long loses seed to shattering, birds and rain.
Part of Community Seed Bank Management
Seed maturity is the stage at which the embryo has finished filling and the seed will germinate and store well.
Eating Ripeness And Seed Ripeness Are Different Stages
A lettuce, a bean pod or a cucumber is picked for the table well before its seed is finished. Seed keeps developing after the eating stage: it fills with stored food, loses water and hardens its coat. Seed taken early is small, shrivelled or soft and will not store. So for each seed crop, mark the plants you will save from early and leave them alone while you eat from their neighbours.
Dry-Seeded Crops: Wait For Brown And Dry
Beans, peas, grains, lettuce, sunflower and herbs such as dill and coriander ripen their seed on the plant.
| Crop | Sign that it is ready | How to take it |
|---|---|---|
| Beans, peas | Pods brown and dry; seeds rattle | Pull whole plants and hang to finish drying |
| Wheat, oats, corn | Heads golden; grain too hard to dent | Cut heads, then thresh and winnow |
| Lettuce | Seed heads fluffy | Cut into a bag and shake |
| Sunflower | Back of head brown, seeds dark | Cut head, dry indoors, rub out seed |
| Dill, coriander | Seed heads brown | Cut into a bag and shake |
Seed on one plant does not ripen all at once. Lettuce and brassicas ripen over days or weeks, and pods at the base open before the tip is ready. Waiting for every pod means losing the first ones to shattering. The existing seed-processing guide suggests cutting when most of the pods or heads are mature rather than all of them (Dry Seed Processing), then finishing the drying under cover.
Wet-Seeded Crops: Take The Fruit Past Eating Stage
Tomato, squash, cucumber, pepper and melon carry their seed inside the fruit.
- Tomato: fully ripe fruit is enough; overripe is fine.
- Squash and pumpkin: hard rind and dry stem, so the fruit is fully mature.
- Cucumber: overripe, yellow to orange, well past eating stage.
- Pepper: past green, at the fully coloured stage.
Then extract and dry the seed (Wet Seed Processing). A cucumber that looks fine at the green stage holds seed that is not mature.
Biennials Flower In The Second Year
Carrot, beet, onion, cabbage and kale set seed in their second year, after winter. Keep a sound root or plant through the cold (Overwintering Biennials) and expect the seed harvest a full year after sowing.
Dry Seed Fully Before It Is Stored
Seed that is hard on the plant is still wetter than it should be for storage. Spread it thin and finish drying indoors in warm, airy conditions (Desiccants and Moisture Control).
Common Mistakes
- Harvesting at eating ripeness. The seed looks complete and germinates badly.
- Waiting for every pod. The early pods have already dropped their seed.
- Leaving plants out in rain at the dry-down stage. Seed can sprout in the pod or mould; cut and finish under cover when rain threatens.
- Saving from the plants that were picked over for food. Mark seed plants early.
What’s Next
- Learn next: Cleaning and Processing by Crop Type — what to do with the seed once cut
- Combine with: Harvest Timing — the Phase 2 guide to the same decision