Save seed only from open-pollinated plants. Plants that pollinate naturally without special manipulation are called open pollinated. Open-pollinated plants produce true-to-type seed–meaning their seedlings are like their parents.
Open pollinated varieties are the result of the repeated natural selection of superior plants from the same strain or variety. Open-pollinated plants are essentially identical genetically through natural selection and pollination.
(Remember that plants can be either self pollinated or cross pollinated. Cross pollination can occur naturally by insects or the wind–resulting in an open-pollinated plant–or by design and outside manipulation–human plant breeding, resulting in a hybrid. Open pollinated plants that are not self pollinating are susceptible to cross pollination by a different strain or variety of the same species. This may produce plants with mixed traits not suitable for seed saving; this, for example, can happen if a pollinating bee carries the pollen of a different plant strain or variety to the plant it pollinates.)
Only open pollinated plants are suitable for seed saving. Seed from hybrid plants commonly do not grow true-to-type. Hybrid plants are produced by selection, manipulation, and breeding of parent lines. While hybrids combine the best traits of their parents, the seed of hybrids usually revert to the less desirable characteristics of the generations that came before.
Open pollinated plants that most easily produce true-to-type seed are those that are self pollinating. A self pollinating plant has male and female parts in the same flower or separate male and female flowers on the same plant. Self pollinating plants commonly produce seed true-to-type because there is a very short distance for the pollen to travel to achieve pollination. Self-pollinating vegetables include beans, chicory, endive, lettuce, peas, and tomatoes.
Plants cross pollinated by insects and the wind will produce true-to-type seed as long as the pollen comes from the same strain or variety of plant.
How to save seeds (a step-by-step guide):
• Save seed from the best open-pollinated plants in your garden; the plants that have the best characteristics of the variety you want to grow, that are healthy, vigorous, and yield well. Do not save seed from diseased plants or plants which have set seed prematurely as the result of weather stress.
• Grow one vegetable cultivar at a time if you intend to save seed. That way there will be no risk of cross pollination.
• Remove from the garden plants that are not true-to-type before they flower–this culling process is called “rouging out.” This ensures inferior plants will not cross pollinate with plants you want to grow on.
• Do not grow differing cultivars of the same plant next to each other. This could result in unintended cross pollination. (Cabbage, corn, pumpkin, and squash are plant families that easily cross-pollinate.) Keeping true-to-type is important when saving seed.
• Do not save from F1 hybrids (human manipulated and bred plants); they will not breed true-to-type.
• To avoid unintended cross pollination of different plants from the same genus, isolate the variety from which you intend to save seed. Grow that variety in a greenhouse or poly-tunnel or at least 200 feet or more from other varieties of the same genus. The distance pollen can travel varies from plant to plant. Fences and hedges can cut down on the risk of cross pollination.
• Mark the plants you are growing for seed saving with a stake; you don't want to harvest these plants by mistake.
• Keep plants well watered when until seed heads form following flowering. When seed heads form stop watering and allow seed pods to turn from green to yellow to brown.
• Stake or tie plants as necessary to keep seed pods from falling on the ground and becoming soiled.
• Allow seed pods to dry naturally on the plant, but before dried pods burst or are spoiled by rain or eaten by birds or pests cut them from the plant and place them in a cool, dry place where they can burst naturally or be opened and the seed saved. Hang plants upside down to dry completely. Place a newspaper beneath to catch falling seed. If you can not cut seed heads from the plant cover the seeds heads or pods with a bag to catch the ripened seed.
• When the pods are brittle and dry, shake out the seed onto the newspaper to dry. Be sure to write the name of the plant cultivar on the paper catching the seed.
• Store dry seed in paper envelopes or jars in a cool, dry place. Be sure to label the seed storage containers.
• Seed from fleshy fruits such as tomatoes, squash, and cucumbers is saved from fruits that are allowed to get a little overripe on the plant before harvesting but before they begin to rot.
• Separate the seed from the flesh and wash the seed in clean water before drying, e.g. cantaloupe, squash, and cucumber
• If the seed has a jelly coating–such as tomatoes, remove as much of the flesh and jelly coating as possible by letting the seed sit in a jar of water for a few day. The seed will sink to the bottom and the jelly pulp will float to the top. Pour off the pulp and dry the seeds.
• Plants for seed saving need dry weather to ensure the seed heads and pods develop disease free. If the weather in your region is wet during seed saving time, it may be better to buy quality seed.