How do I save seeds from my garden plants so they'll grow true next year?

Seed saving works reliably for self-pollinating crops with little cross-pollination risk: tomatoes, peppers, beans, peas, and lettuce are the most forgiving starting points. Tomatoes, for example, are nearly always self-pollinated before a bee can cross them with another variety. Open-pollinated and heirloom varieties produce offspring genetically similar to the parent plant. Hybrid (F1) varieties — usually labeled as such on seed packets — produce unpredictable offspring that may not resemble the parent plant and are generally not worth saving for true reproduction.

Select seed from the best fruit on your healthiest plants. For tomatoes: let the fruit ripen fully and slightly past peak eating quality before harvesting seed. Scoop seeds and surrounding gel into a glass with a small amount of water and let it sit at room temperature for 2–3 days. The gel ferments and separates from the seeds, which sink to the bottom. Pour off the floating material and pulp, rinse the seeds well, and spread them on a non-stick surface (a ceramic plate or screen, not paper towels — they stick) to dry completely. For beans and peas, let pods dry on the plant until the seeds rattle inside, then shell them out. For lettuce, let seed heads fully brown and dry on the plant before cutting; the tiny seeds fall easily.

Drying is critical. Seeds must be thoroughly dry before storage — residual moisture causes mold and rapid loss of viability. Dry seeds in a warm room with good airflow for at least two weeks. A simple test: bend the seed. A properly dried seed snaps; a moist seed bends. Store in small paper envelopes or glass jars with tight lids, labeled with variety and year. Include a silica gel desiccant packet if you have one. Keep stored seed cool and dark — a refrigerator at constant temperature is a good option. Avoid freezing unless seeds are extremely dry (below 8% moisture); fluctuating freeze-thaw cycles can damage seed.

Viability varies by species. Tomato and pepper seeds kept well can remain viable for 4–5 years. Bean and pea seed is reliable for 3–4 years. Onion, parsnip, and leek seed viability drops sharply after one season and saving them is generally not worth the effort. Corn and squash cross-pollinate readily with neighboring varieties — saving them true to type requires isolating plants by distance or timing, which is workable but requires more planning than self-pollinating crops. Before planting saved seed, a germination test on a small sample confirms viability and tells you whether to plant more densely or buy fresh.