Saving seeds from your favorite open-pollinated Solanum lycopersicum varieties is a rewarding way to preserve the genetics of the best-tasting fruit in your garden. By following a simple fermentation process, you can ensure high germination rates for years to come.
Selecting Your Fruit
To save seeds, you must choose open-pollinated or heirloom varieties. Hybrid tomatoes will not grow true to type, meaning the offspring may look or taste significantly different from the parent. Select the healthiest, most flavorful fruit from a plant that has performed well throughout the season in your USDA zone. Allow the tomato to become slightly overripe on the vine to ensure the seeds have reached full maturity.
The Fermentation Process
Tomato seeds are encased in a gelatinous sack that inhibits germination and contains growth inhibitors. Fermentation removes this coating while also killing many seed-borne diseases.
- Slice the tomato in half across the equator and scoop the seeds and pulp into a clean glass jar.
- Add a tablespoon of water if the pulp is dry, then cover the jar with a breathable cloth secured by a rubber band.
- Let the mixture sit in a warm spot, roughly 70°F to 80°F, for two to four days until you see a layer of mold form on top.
Tip: Watch your jar closely; if you leave the seeds in the fermentation mix for more than five days, they may begin to sprout right in the liquid.
Cleaning and Drying
Once the fermentation is complete, it is time to isolate your seeds. The good, viable seeds will settle to the bottom of the jar.
- Gently pour off the moldy top layer and add fresh water to the jar. Swirl it, let it settle, and pour off the debris until the water runs clear and only clean seeds remain at the bottom.
- Spread the seeds in a thin layer onto a piece of fine-mesh screen or a non-stick parchment paper surface. Do not use paper towels, as the seeds will stick permanently.
- Allow them to air dry in a well-ventilated area for about one week.
Proper Storage
Once fully dry, store your seeds in a paper envelope in a cool, dry, and dark location. Label each packet with the variety name and the year of harvest. Stored correctly, tomato seeds remain viable for four to six years, providing you with a constant supply for every future spring planting.