Saving your own tomato seeds from homegrown heirloom tomatoes will give a better tasting and producing tomato as it adapts to your location in just a couple of years. You only need a few fruits and some simple tools to get started.
A few considerations on saving your own tomato seeds: select fruit that are fully ripe or even just slightly overripe to get mature seeds; choose fruit with the characteristics that you are looking for — best-looking, best-tasting, earliest, latest or perhaps, largest. This will help you achieve more of the same qualities next year.
Finally, make sure that you are choosing open-pollinated or heirloom tomatoes, as hybrids from the store won’t grow true to what you started with. Saving some of your own seeds helps carry on an ancient gardening tradition many generations old.
The fermentation method duplicates what happens naturally when a tomato falls off the vine, ferments and then rots, leaving the seeds ready to germinate next spring.
During the fermentation process, microorganisms such as bacteria and yeast destroy many seedborne pathogens that can affect the next generation, while removing the gel coat around the seeds that contains germination inhibitors. The fermentation method provides the added benefit of removing bad or low-quality seeds.
Saving Tomato Seeds: The Process
To get started, you will need a clear container such as a pint canning jar or plastic container, a metal mesh strainer fine enough so that the seeds can’t slip through, paper or cloth towels for drying, a sharp knife and a good sampling of your best heirloom tomatoes.
Cut the tomatoes in half widthwise or at the “equator” of the blossom end and vine end, exposing the seed cavity. Using your finger, a small spoon or butter knife, scoop out the seeds into a jar. With smaller tomatoes, cutting an X in the end and squeezing the seeds out works well. If there isn’t much liquid, add some water (no more than ½ cup non-chlorinated water to 1 cup pulp and seeds). Chlorinated water will inhibit the fermentation greatly.
Set the jar or jars in a warm but not hot location where they can ferment and be undisturbed for three to five days. They will have a very strong odor, so inside might not be the best place. After a day or two, a layer of white mold will form on the top. This is what you want, don’t disturb it! The fermentation is finished when the gelatinous seed coats float and the white mold covers the surface. Add water and stir vigorously, letting the mature and viable seeds sink to the bottom. The gel coats and poor quality seeds will be at the top.
Gently pour the pulpy mixture off the top, adding water and repeating until only the mature seeds are at the bottom. Pour the seeds into a strainer and give a final rinse to remove any clinging gel coats, gently rubbing the seeds on the strainer under running water. Dry the bottom of the strainer and pour the seeds into a glass, ceramic or plastic dish to dry.
Separate the seeds from touching to ensure complete drying and stir twice a day. Dry the seeds in a warm place, not over 95°F. Do not dry the seeds on paper towels, cloth or flexible plastic as they will stick and be difficult to remove. The seeds should be dry after two to three days. Make entirely sure that the seeds are completely dry, or they will mold and not be viable for next year. Store them in a labeled container in a cool, dry location for next year.
By Stephen Scott. This article appeared in the January 2014 issue of Acres U.S.A.
Stephen Scott is an heirloom seedsman, educator, speaker, soil building advocate, locavore, amateur chef, artist and co-owner of Terroir Seeds with his wife Cindy. They believe in a world of healthy soil, seed, food and people.