ISOLATION: Ashworth puts much emphasis on avoiding cross-pollination, although this is most easily avoided by only planting one variety of each kind of plant in your garden (of course this won't work if your next door neighbor has a lush garden of different varieties). A good rule of thumb for "isolation distances" is a half mile for most vegetables, and about 1 mile for corn. Ashworth gives some alternatives to distance isolation. Time isolation involves planting the first variety as early in the season as possible. When the first crop is beginning to flower, sow the second variety. Time isolation is only successful if the first crop sets its seed before the second flowers. This method usually works best in varieties that have very different maturing dates. Some examples of varieties that work well with time isolation are corn, sunflowers, and lettuce.
Mechanical isolation, by either caging or bagging, seems exceedingly tedious and time consuming, but may be necessary for the hobbyist whose interest is preserving the genetic heritage of the seeds. If this is you, I highly recommend purchasing or obtaining Seed to Seed from your local library.
SELECTION: Seed saving doesn't begin at harvest. It is important to monitor the plants from germination to select seeds that are "true-to-type" to obtain seed that is representative of that variety. Observe the plants growth and note not just the fruit, but the earliness of the plant, disease resistance, insect resistance, drought resistance, stockiness, vigor, color, lateness to bolt, and hardiness. Remember, too, that if the best of each harvest goes on the table and only the poor examples are saved for seed, next year's harvest will be representative of those poor examples!
Roguing out off-type plants is difficult when growing for food as well as seed saving in a home garden. Letting an off-type plant remain in the garden is fine, as long as it isn't allowed to cross-pollinate and seeds are not saved from these plants.
SEED CLEANING It's important to clean the seeds to prepare them for storage. There's two types of cleaning methods, wet processing and dry proc:essing. With wet processing, vegetables such as tomatoes are extracted from the fruit, fermented, and then dried. Fermentation may sound excessive, but during this process microorganisms have a chance to remove seed-borne diseases that can affect the next generation of plants. Other seeds just need to be scrubbed in a wire colander to remove debris from such moist seeds as those from squashes. So here's the lowdown on fermentation:
First remove seeds from the fruit. This can usually be accomplished by mashing the fruit (from small fruit like tomatoes) depending on the species, some may have to undergo fermentation. When fruits fall to the ground they ferment to some degree as they rot in their juices. Some microorganisms destroy seed-borne disease and ensure a healthy seedling. You should not add water to the mix as dilution may slow process and cause seeds near surface to sprout. For example, for tomatoes, fermentation is necessary also to remove the gel sack before drying. First you squeeze tomatoes of one variety into labeled deli tubs (no lid), and after about three days there's a fungal growth on top. Then pour contents of deli tube thru strainer and rinse with, let's say, a hose as you pour. As the mold stinks, don't keep it in your house where pets and children can knock it over. Fermentation is finished when bubbles begin to rise to surface or mold completely covers surface. Add enough water to double mixture, and you will find that the good seeds settle to the bottom while the others and debris can be poured off.
DRY PROCESSING: Some plants can be processed by allowing to dry on the vine, in the case of some beans; being hung to dry on the plant (pulled up before seed falls and hung in barn to dry). Corn is removed from the cob after drying. Sorghum can be hung to dry and, when ready to sow next season, the heads can be cut open and the tiny seeds easily distributed from the palm of your hand. Remember that some plants can be eaten from and still produce seed (such as lettuces and fruitful plants). Others must be undisturbed until they go to seeds (radishes, beets, most root crops). Some root greens are tasty, my favorites are those from beets, but many people all over the world cook with peanut and other greens. Just remember to leave some stalks to produce seed.
All seeds need to be dried, including those that went through wet processing. Place in a warm dry area on cookies sheets, or something of smooth material they won't stick to (not like paper towels!). Any time the temperature may rise above 96 degrees, seeds may be damaged. So do not leave them to dry in the summer sun, or place them in the oven. The top of your refrigerator is a nice warm place! Stir them around every couple of days to see if they're ready and to keep them from sticking to the pan or each other.
If seeds are dried in the pod, sometimes it is difficult to remove them all by hand. Bean and pea pods, radishes and carrot umbrels are all allowed to dry in the garden whenever possible. Dry seed heads or pods are rubbed, beaten, or flailed to remove seed. This is often referred to as threshing. Sometimes dry seed pods are placed in a sack and jogged on or flailed. But too vigorously threshing the seed may cause it to split or produce hairline cracks in corn.
Winnowing may be necessary to remove dry, flaky debris on seeds that may trap mold or disease. Using the wind, a vacuum cleaner engine, or a hairdryer, spill seeds from one bowl to another thru breeze. Place a tarp under to trap escaped seeds. If seeds and chaff are the same weight, winnowing is difficult; Instead use a large screen to shake out seed or chaff, depending on the size of the mesh.
STORAGE: Home-saved seeds will retain their vigor if thoroughly dried and saved in air proof containers in the freezer for extended storage or in cool cellar for next season. Glass and metal are the only two common materials that are completely moisture-proof. Make sure you label everything. I promise that you will forget by next spring, if not next week! A little box of 3"x 5" cards is easy to keep with your gardening tools and can follow the plant all the way to seed or the meal on your table.