Roaming insects pay little attention to human classifications. This sometimes laborious method involves the hand transfer of pure pollen from the stamen of one flower to the virgin stigma of another. It is used when you want to be as sure as you can be that your seeds are pure. Male and female flowers are protected from insects before they first open and when they have developed, watching for stray insects, they are unsealed and pollen is transferred with the stamen itself or a fine paintbrush. The female flower is then protected in some way from contamination by other foreign pollen.
Methods vary for individual plants.
It is good to leave the seed body on the plant longer than if you were going to eat it, especially for those plants which are eaten immature. For wet plants harvest as you would to eat, then leave inside for a while for the seeds to finish maturing. For seeds that dry on the plant, try to harvest on a dry day and if bad weather or frost looms, pull the entire plant and bring it inside to ripen. Methods vary for individual plants. Wet cleaning Seeds that come within a wet body should be washed in water until all flesh is removed, then placed in a warm place on a plate or paper strip to dry naturally.