The seeds that heirloom-seed gardeners hold in their hands at planting time are living links in an unbroken chain reaching back into antiquity. Old varieties are threatened today, not because of any deficiencies, but because they are not suitable for factory farmers and the food processing industry. The old varieties will survive and flourish only if they continue to be grown by backyard gardeners.
Seed cleaning methods can be divided into wet processing or dry processing. Here are three-step directions for wet processing seeds that are embedded in the damp flesh of fruits or berries, such as tomatoes, cucumbers, muskmelons or ground cherries.
Three Steps to Wet Processing Seeds
1. Removal of Seeds
Large fruits are cut open and the seeds are scraped out. Small fruits are usually crushed or mashed. The seeds, pulp and juice from the fruits may need to go through a fermentation process. During the fermentation process, microorganisms such as bacteria and yeast destroy many of the seed-borne diseases that can affect the next generation of plants.
2. Washing Seeds
The process for washing seeds to remove them from the surrounding pulp or to separate them from the fermenting mixture is basically the same. The seeds and pulp are usually placed in a large bowl or bucket. Add at least twice as much water as the volume of seeds and pulp, and stir the mixture vigorously. Viable seeds tend to be more dense and sink to the bottom, but poor quality seeds tend to float. Add more water and repeat the process until only clean seeds remain. The seeds are then poured into a strainer and washed under running water.
3. Drying Seeds
Dump the cleaned seeds onto a glass or ceramic dish, cookie sheet, window screen, or a piece of plywood. Do not attempt to dry the seeds on paper, cloth or non-rigid plastic, because it can be extremely difficult to later remove the seeds from such surfaces.
Spread the seeds as thinly as possible on the drying surface and stir the seeds several times during the day. Always remember that damage begins to occur whenever the temperature of the seeds rises above 95F. For that reason never dry seeds in the oven. Even at the lowest settings, the temperatures in an oven can vary enough to damage the seeds.
Never dry seeds in the direct sun if there is any chance that the temperature of the seeds will exceed 95F. Always remember that the air temperature is often not the same as the temperature of the seeds. Even at air temperatures around 85F, dark colored seeds can sometimes become hot enough to sustain damage.
Fans hasten the drying process; ceiling fans are ideal, and placing seeds on window screens is best of all as they allow for excellent air circulation.