Guest post by Diane Ott Whealy*, photo courtesy of Seed Savers Exchange.
Tomato seeds are ready for harvest when the fruit is ready to eat. Slice open a tomato along its equator and squeeze seeds, juice and pulp into a jar. Let this mixture sit and ferment for a day or two before you rinse off the seeds in a fine mesh colander. Set the seeds out to dry on a coffee filter in an airy location out of direct sunlight for 3-4 days before storing.
Download tomato seed-saving sheet below.