Harvesting seeds after you have harvested your vegetables is economical and rewarding; however, while vegetable seeds are not difficult to collect, growing the "parent plant" can be challenging. Plant a simple garden of self-pollinating vegetables, or go the extra mile to isolate vegetables that may cross-pollinate. Certain vegetables must be separated by several feet or more to prevent any cross-pollination, which may make seeds that are not viable. Once you have planned and planted your garden, you'll find making your own vegetable seeds a very enriching experience.
Allow fruit on your non-hybrid plants to over-ripen. Spinach and lettuces need to go to seed. If there is danger of frost, pull up the plant and hang it to dry in a cool, dry location.
Place the pulp and seeds of cucumbers or tomatoes in a jar with a little water. Let the pulp ferment and grow a fungus, which will eat the seed protection as well as prevent seed disease.
Pour off the water, pulp and any floating seeds from the jar. Place viable seeds on a paper towel to dry.
Scoop out the seeds of pepper, squash and melons to place them on a paper towel or newspaper to dry.
Remove the seeds of peas, radishes, beans, lettuce, spinach and corn (from the pod, stalk or cob) by hand after these seeds have dried.
Store seeds in resealable plastic bags in a cool, dry place.