How to Save Your Tomato Seeds - This is a really simple process.
Here's how...
1. Choose a ripe tomato.
2. Cut it across the equator of the fruit.
3. Squeeze the seeds, gel, and juice out into a small cup or jar.
4. Cover the seed gunk with two to three inches of water.
5. Label your container so you know which variety of tomato you saved
seeds from.
6. Set the labeled jar in an out-of-the way spot and wait.
7. After about three days, white mold will start to form on the surface
of the water. This means that the gelatinous coating on the seeds has
dissolved.
8. Once you see the white mold, pour off the mold, the water, and
any seeds that are floating (floating seeds are bad - they wouldn't have
germinated.) You want all of those seeds sitting at the bottom of the cup.
9. After you've poured the mold and bad seeds off, drain your seeds in a fine mesh strainer and rinse under running water. It's not a bad idea to move the seeds around with your fingers to remove any extra gel that may be clinging to them.
10. Dump your rinsed seeds onto a paper plate
11. Make sure your seeds are in a single layer on the plate, and set it aside a few days so the seeds can completely dry.
12. Once they're dry, put them in a labeled envelope, baggie, or other container and store in a cool, dry spot.
Tomato seeds will keep well and germinate reliably for up to ten years if stored properly.