Saving Heirloom Tomato Seeds

The following is derived from a post originally at The Sustainable Food Center:

Every heirloom tomato you buy at the Farmers' Market comes with a fairy-tale prize inside: generation after generation of tomato plants, neatly packed away within each one! Heirloom tomatoes are treasured for their flavor and variety, and, like the keys to a kingdom, their seeds are shared and passed down from grower to grower like the priceless inheritance they are. With just a little effort and knowledge, you'll be starting your own tomato dynasty soon enough. Read on for the basics of what you need to know to start saving seeds right now! (hint: now is the time--once tomatoes go out of season, you'll have to wait another year)

HOW TO SAVE HEIRLOOM TOMATO SEEDS:

1. Harvest seeds: Cut the tomato in half. Use your finger or a knife to scoop out the seeds and juice from their cavities, or squeeze the tomato over a glass jar. Use a small jar, such as a jelly jar, if you are only saving seed from one or two tomatoes. Once the seeds and all their juice is in the jar, add no more than 25% water and slosh it around.
2. Let them sit: Place the jar somewhere warm for two or three days, stirring occasionally.
3. Check for readiness: After a few days (depending on the weather), a mold should form on the top. This method mimics the rotting of the tomato in nature or the actions of the digestive system of an animal and breaks down the clear gel coating around the seeds, which prevents the seed from sprouting inside the tomato. Once the mold covers the entire top of the liquid and the seeds have begun to sink, the gel coating has been broken down and they are ready for cleaning.
4. Separate: You know seeds are ready for their final cleaning when most of them have sunk to the bottom of the jar. Add water to fill the jar and slosh it around. Let it settle for a moment. Carefully pour the water out of the jar. The mold, pulp, and immature seeds should sink and stay in the jar.
5. Clean: Repeat this decanting process two to five times until you have only clean seeds and clean water. Pour out as much water as you can without losing the seeds or pour it through a fine mesh strainer.
6. Dry: Pat dry through the strainer and then scoop the seeds out onto a small plate (like the lid from a yogurt container). Allow to dry without intense heat.
7. Store: When they are very dry, store the seeds in a moisture-proof container in a cool, dry place. It is very important to label the container with variety and date. Tomato seeds can last for ten years or more if stored in a cool, dry spot.