If you decide to make use of your local seed library, remember you have to harvest and dry your seeds before returning "borrowed" seeds. All it takes is a few simple steps.
First, start with healthy plants. Harvest seeds from your most robust fruits, vegetables, or perennials. The steps differ only slightly, depending on whether the seeds are wet, like a tomato's, or dry, like a sunflower's. Here's what to do in each case.
For Dry Seeds
1. Let the plant flower and dry-out on the stem, then clip off the head before the seeds scatter.
2. Store flower heads in a warm, dry place on a tray until the seeds drop off. A paper bag with a few air holes will catch the smallest seeds when cuttings are upended.
3. Pass heavy seeds, like allium, between two cups in front of a fan; the breeze will blow away light debris. For smaller seeds, like lettuce, use a kitchen strainer.
4. Use a window screen to cure seeds for one week for dry seeds
For Wet Seeds
1. Pick the fruit or vegetable a few weeks past its typical harvest time but before it rots. Scoop out the seeds.
2. Let the seeds sit in room-temperature water for three days. This helps remove the film and gives dud seeds a chance to float to the top.
3. Rinse with running water in a kitchen strainer, and rub them to remove any residue.
4. Use a window screen to cure seeds for two weeks for wet seeds. Put in paper envelopes or plastic containers; note the plant name and the cultivar. Keep cool and dry.