Seeds That Need More Time
Eggplants, cucumbers, and summer squashes must ripen beyond the normal, ready-to-eat stage to allow viable seeds to develop inside.
To save the seeds of your eggplants, you’ll need to wait until the fruits are far past the stage when you’d pick them for eating. Any seeds saved from table-ready eggplants will be immature and won’t be viable. If left on the plant, purple eggplant varieties will ripen to a dull brownish color, green varieties to a yellowish green, and white varieties to golden. Eggplants ready for seed saving will be dull, off-colored, hard, and sometimes shriveled.
Cut the ripe eggplants in half and pull the flesh away from the seeded areas. If you want to save more than a few seeds, use a food processor or blender to mash the flesh and expose the seeds. Process (without peeling), and put the pulp in a bowl. Add water, let the good seeds settle, and then pour off the water and debris. Repeat until only clean seeds remain. Add a bit more water and pour the mix through a strainer with a mesh fine enough to catch the tiny seeds. Dry the bottom of the strainer with a towel to absorb excess moisture and dump the seeds out onto a plate to dry.
After cucumbers ripen, they change color and become soft. (Remember, if you stop picking cucumbers, their vines will stop producing new fruit, so pick your fruit for seed saving toward the end of the season.)
Cut the ripe cucumber in half and scrape the seeds into a bowl. To remove the seeds' coating, rub them gently around the inside of a sieve while washing them or soak them in water for 2 days. Rinse and dry. (Note: Make sure the cucumbers you use for seed are disease-free; some diseases can be carried on seed and could affect your future crop.)
You’ll need to let summer squashes ripen past the tender stage, too. When you can’t dent the squash with a fingernail, the fruit is at the right stage for seed saving. Pick it, cut it open, scrape the seeds into a bowl, wash, drain, and dry.
Keep Reading: How to Read a Seed Catalog