Seed saving is something that has gone the way of processing your own chickens and milking the family cow... it's something nobody does anymore. Most folks probably wouldn't even know where to begin. Before I got here, I certainly didn't.
Most seed saving that happens at the home gardener scale is for heirloom plants. Heirloom vegetables are usually older varieties, although there are some exceptions, and are open pollinated,* which also means that the second generation will be the same as the first generation.** Heirloom varieties are usually known for their flavor, and often look a little funky, especially to those used to buying mono-vegetables at the supermarket that are all bred to look flawless and exactly the same.
These are some big differences from hybrid plants you usually buy from stores - if you save seed from a hybrid, the third generation will be quite different from the second generation, which is what you planted. If you remember your high school genetics lessons, you'll see why - the third generation will have recessive characteristics from the first generation that don't show up immediately. As a result, seed companies have a monopoly over that seed. Anyone who wants Sun Gold Tomatoes has to buy their seed year after year if they want the same product.
How you save seed depends on the vegetable. Tomatoes, watermelons, eggplant, cucumbers and squash are wet processed; beans, corn, lettuce, brassicas, spinach and peppers are dry processed (although peppers can be wet processed, as you will see). Last week, Autumn and I visited Twin Oaks Intentional Community and Southern Exposure Seed Exchange as part of the CRAFT program, where they did demonstrations of various types of seed saving.
Wet processing involves cutting or smashing up the vegetable in question and letting it ferment for several days. This, by the way, is definitely the best-smelling part of the process.
Then you add water and pour off the pulp and floating seeds, and keep adding water and pouring until the water runs clear. Then the seeds are put on a screen, where they dry out, which should take about a week. Once they're dry, they're ready to be stored.
With dry processing, the process depends on the plant, but often involves crushing everything together (most memorably by sandwiching the plants between tarps and dancing on them) and then winnowing the seeds using a fan.
We're actually saving seed for Southern Exposure this year at the farm, so the demonstrations helped us answer a lot of questions.
One of the vegetables we're growing for seed is Lipstick Pepper, a red pepper that is incredibly sweet and delicious.
We decided to wet process our peppers, since it seems to be a slightly easier process than scraping all the seeds off by hand. First, you cut out the crown of the pepper, with the seeds still attached.
You put all the pepper crowns in a container...
...and cover them with water. Let them sit for a day. The seeds are then much easier to remove by hand. After removing the seeds, you add more water and pour off the excess water and the floating seeds. You keep adding water and repeating until the water runs clear - with peppers, that takes maybe one or two more tries. (Tomatoes take forever.)
The seeds go on a screen in a well-ventilated area (preferably with a fan running). They need to dry for five to seven days. And voila! Home-processed pepper seeds.
*Open pollinated plants are pollinated naturally by insects, wind, etc. They are not self pollinating.
**Assuming you didn't accidentally cross pollinate your plant with another type, that is. For open pollinated plants, this is a real possibility. Isolation distances to prevent crossing differs from plant to plant, from 40 feet for string beans and lettuce to 600 feet for corn and squash.