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Harvest, Storage & Post-Harvest TimingHarvest Timing for Seed Crops
Harvesting seed is a different job from harvesting food. The plant has to finish its life cycle first, and the seed needs to be mature, not just full sized.
Key points
- Seed comes from mature plants, so plan to leave some plants in the garden longer.
- Sort crops into dry-seeded and wet-seeded groups to know what signs to watch.
- Cut and finish drying plants indoors if wet weather is coming.
- Check state rules before selling seed.
How is seed harvest different from food harvest?
Most vegetables are picked before they are mature, while seed has to come from fully mature plants. A cucumber eaten for slicing is picked young, and a cucumber left for seed has to stay on the vine until it is well past eating stage. The same is true of squash, beans and many greens.
That means seed saving needs extra time in the garden and a plan for which plants you give up for seed.
What are dry-seeded and wet-seeded crops?
Growers often sort seed crops into two groups. Dry-seeded crops, such as beans, peas, lettuce, many flowers and many herbs, are harvested when seed heads or pods have dried on the plant. Wet-seeded crops, such as tomatoes, cucumbers, squash and melons, carry seed inside moist fruit that must be fully ripe or past ripe.
The group tells you the signs to watch for and the cleaning method later. Ask your extension office or a seed saving guide for the specific method for each crop.
- Dry-seeded: pods or heads turn brown and dry on the plant
- Wet-seeded: fruit is fully ripe or beyond for the crop
- Biennials, such as carrots and onions, need a second season to flower and set seed
What signs show seed is mature?
For pods and heads, look for a color change from green to tan or brown, and for pods that rattle or split. Seeds should be hard and fully colored for the type. Many flower and herb heads dry on the plant, and seed may shatter if you wait too long, so check often as drying begins.
For fruit crops, the fruit should be fully ripe for its type. Seed is cleaned from the pulp afterward. If the seed looks thin, pale or shriveled, it may not be mature enough to germinate.
Mark the plants you intend to save seed from early, with a tag or tape, so nobody picks them by mistake.
How does weather affect the timing?
Wet weather at seed maturity is a problem. Seed can sprout in the pod, mold, or rot, and heads can mildew. If rain is coming and seed is nearly ready, many growers cut whole plants and finish drying them indoors on screens or paper in a dry, airy place.
Dry, windy weather can cause shatter, which means seed is lost on the ground. Cutting heads into a paper bag helps catch loose seed. Frost can end the process early, so use your first frost date as a deadline for tender crops.
What about cross-pollination and variety purity?
If you want seed that comes true, you must manage pollination. Some crops cross with others of the same species, and distance or physical barriers are used to keep varieties apart. Self-pollinating crops such as beans, peas and tomatoes are the easiest for beginners.
Hybrid varieties do not come true from saved seed, so seed from them can give different results. Ask your seed source or extension office which varieties are open-pollinated.
How should you clean and store seed?
Seed must be fully dry before storage, since moisture invites mold and shortens life. Cleaning removes chaff and pulp, and labeling with crop, variety and year is important.
Storage conditions affect how long seed stays viable, and recommendations vary. We do not give specific temperatures or times here. Your extension office or a reputable seed saving guide can tell you how to store seed for your crops, and a simple germination test before planting tells you how well it kept.
What rules should you know before selling seed?
Selling seed is regulated in many states, and labeling and testing rules can apply. Check with your state department of agriculture before offering seed for sale. Some crops, such as certain protected varieties, may be legally restricted.
If you are only saving seed for your own garden, rules are less of a concern, but it is still wise to avoid saving seed from plants that had disease problems.
Sources and further reading
Last reviewed: November 2026. Educational information, ranges only. Confirm timing with your county extension office.