Quick Answer
Harvest seeds from heirloom vegetables and flowers when the seed heads are fully dry and the seeds rattle inside, usually 1-3 months after flowering, depending on the plant's specific variety and climate.
Determining Seed Readiness
To harvest seeds from heirloom plants, first, observe the seed heads closely. When the seeds are mature, they will be dry and the seed pods will have split or changed color. For example, in tomatoes, the seed pods will turn brown and the seeds will rattle inside. In corn, the silk will dry and turn brown. Check the seed heads daily, ideally in the morning, to determine the optimal time for harvest.
Harvesting and Processing
When the seeds are ready, harvest the entire seed head and place it in a paper bag or a dry container. Allow the seeds to continue drying for a few days, then remove the seeds from the pods and clean them by hand or using a small sieve. For large seeds, such as beans or peas, use a small, shallow dish to winnow the seeds from the chaff. For smaller seeds, such as those from herbs or lettuce, use a fine-mesh sieve to separate the seeds from the debris. Store the cleaned seeds in an airtight container, such as a glass jar or envelope. Label the container with the plant’s name, date, and any relevant notes about the seed’s characteristics.
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