Seed saving is not always feasible with all types of vegetables, but collecting your own seed can be an exercise in self-sufficiency and a lesson in plant biology. Seeds you save from your home production system are accustomed to your climate and growing medium and are adapted to pests in your area. Seeds are generally saved from annual and biennial plants. Perennials are usually propagated through division or cuttings.
The easiest seeds to save are open-pollinating, non-hybrid annuals. Plants that are not self-pollinating can cross-pollinate; therefore, it is best to grow only one variety of a plant from which you want to save seed that season. If two varieties of spinach bloom near each other, the resultant seed is likely to be a cross between the two. Different varieties of peppers should be separated by 500 feet to avoid cross-pollination. Melons, pumpkins, cucumbers, and squash need even more personal space--at least a half-mile is required.
Biennials require more work and commitment. These plants do not send up seed stalks until the second season. Biennials include beets, Brussels sprouts, cabbage, carrots, cauliflower, celery, onions, parsley, parsnips, rutabaga, salsify, Swiss chard, and turnips.
Do not save seed from hybrid varieties if you want plants like the parents. Seeds from hybrid varieties produce a mix of offspring, many of which may have different characteristics than the parent. Seed from hybrid vine crops is often quite variable also - squashes, cucumbers, melons and pumpkins often cross-pollinate with other genetically compatible varieties. Unless pollination has been strictly controlled, strange hybrids often result in the next generation.
Among the vegetable seeds most easily saved are non-hybrid tomato, pepper, bean, eggplant, cucumbers, summer squash, and watermelons. Collect seeds from the fully mature, ripe fruit of these plants.
Tomato: The seeds are encased in a gelatinous coating, which prevents them from sprouting inside the tomato. Remove this coating by fermenting it. This mimics the natural rotting of the fruit and has the added bonus of killing seed borne tomato disease. Squeeze the seeds from a fully ripe fruit into a bowl, add water and let stand at room temperature for about three days. Once fermentation occurs, mold will form on the surface of the water. Add more water, stir, then gently scrape mold and debris off the top. Repeat until only clean seed remains, strain, rinse, and leave the seeds at room temperature until they are thoroughly dry.
Peppers: Select a mature pepper, preferably one that is completely red. Cut the pepper open, scrape the seeds onto a plate and let the seeds dry in a non-humid, shaded place, testing them occasionally until they break rather than bend. Leave at room temperature until completely dry.
Beans, peas, and other legumes: Leave pods on the plant until they are "rattle dry." Pick the pods and remove the seeds when completely dry.
Eggplant: Leave the plant on the vine until it is well past the stage when you would pick it for kitchen purposes. Eggplants ready for seed saving will be dull, off-colored and hard. Cut the eggplant in half and pull the flesh away from the seeded area.
Cucumbers: Cucumbers change color after they ripen and start to become mushy. Cut it in half and scrape the seeds into a bowl. Remove their slimy coating by rubbing them gently around the inside of a sieve while washing them or soak them in water for two days. Rinse and dry.
Summer squash: Summer squash is at the seed-saving stage when you cannot dent the squash with a fingernail. Cut it open, and scrape the seeds into a bowl, wash, drain, and dry.
Watermelon: Put the seeds from ripe fruit in a strainer and add a drop of dishwashing liquid to remove any sugar from the seeds.
Storing seeds; Store most seed packets in airtight jars. The exception is legumes, which store best in breathable bags. To keep the seeds dry, fill a small cloth bag with about one-half cup dried powdered milk. Place the packet in the jar beneath the seed packets. Be sure to label your container with the variety, the date, and other pertinent information. Store your seeds in a cool, dark, dry place; a refrigerator is a good choice. Avoid opening the container until you are ready to plant.
Stored seeds will retain their viability for different lengths of time depending on the type of seed. Melon seed can be stored for as long as five years, while sweet corn is only good for one year. Other types of seed remain viable for two to three years.