Collect seeds from ripe tomatoes at the end of the growing season
The best time to save tomato seeds is when your tomatoes are fully ripe — soft to the touch and deeply colored. Pick tomatoes that are healthy and free of disease or pest damage, because seed from a weak plant will carry those weaknesses forward. Let the tomato sit on the counter for a few days after picking so the seeds inside finish maturing.
Cut the tomato in half and squeeze the seeds and gel into a small container or bowl. You will get a slimy mass of seeds suspended in juice. This gel coating actually prevents seeds from sprouting too early, so you cannot skip this step — you have to remove it before storage.
Key Takeaways
- Tomato seeds must be fermented for three to five days to remove the gel coating that keeps them dormant, or they will not sprout reliably.
- Rinse fermented seeds thoroughly under running water, spread them on a paper plate or coffee filter, and let them dry completely in a warm, dry spot for two to three weeks.
- Store dried seeds in a paper envelope in a cool, dark place — a basement, closet, or refrigerator — where they will stay viable for four to six years.
- Label every envelope with the tomato variety and the date you saved the seeds, because unmarked seeds lose their identity and usefulness.
Ferment the seeds to break down the protective gel
Place the seeds and gel in a small jar with a little water — just enough to cover them — and leave it on the counter at room temperature. The mixture will smell bad within a day or two. This is normal. The fermentation process breaks down the gel coating so the seeds can absorb water and sprout when you plant them next spring.
After three to five days, the seeds will sink to the bottom and the gel will have mostly dissolved. You will see mold on the surface of the water, which is also normal and part of the process. When the seeds are loose and the gel is gone, move to the next step.
Rinse and dry the seeds completely
Pour the contents of the jar into a fine-mesh strainer and rinse under running water, rubbing the seeds gently with your finger to remove any remaining gel. Keep rinsing until the water runs clear and the seeds feel dry to the touch, not slimy. This usually takes two to three minutes of steady rinsing.
Spread the clean seeds on a paper plate, coffee filter, or piece of newspaper in a single layer. Place them in a warm, dry spot — a sunny windowsill, a shelf in a closet, or near (but not directly on) a heating vent. Turn them over once or twice during the drying period. Seeds are fully dry when they are hard and brittle, which takes two to three weeks depending on humidity and temperature.
Store seeds in a cool, dark place until spring
Once the seeds are completely dry, place them in a paper envelope and seal it. Write the tomato variety and the date you saved the seeds on the outside of the envelope in permanent marker. Paper envelopes allow seeds to breathe and prevent moisture buildup, which can cause mold or early sprouting.
Store the envelope in a cool, dark, dry place. A basement, a closet shelf, or the vegetable drawer of a refrigerator all work well. Avoid the freezer unless you live in a very humid climate — freezing can damage seeds if moisture gets inside the envelope. Properly stored tomato seeds remain viable for four to six years, so seeds saved this year will grow strong plants in the next three to four seasons.
Label and organize seeds so you know what you have
Unmarked seeds are useless because you will not remember which variety is which. Write the variety name, the date, and any notes about the plant — such as "early harvest" or "disease-resistant" — on the envelope. If you save seeds from multiple tomato plants, label each envelope separately, even if the varieties are the same, because plants can vary slightly from year to year.
Keep all your seed envelopes in one container — a shoebox, a small drawer, or a plastic bin — so you can find them easily in spring. A straightforward list on the outside of the container showing what is inside saves time when you are ready to plant.
Choose the right tomato varieties for seed saving
Heirloom and open-pollinated tomatoes produce seeds that grow into plants identical to the parent plant. These are the best choice for seed saving because the tomatoes you grow next year will taste and look the same as the ones you saved from.
Hybrid tomatoes — marked F1 on the seed packet — produce seeds that do not grow true to type. The plants that sprout from hybrid seeds will be different from the parent plant, often smaller or less productive. If you want consistent results year after year, save seeds only from heirloom or open-pollinated varieties.
Frequently Asked Questions
Can I save seeds from store-bought tomatoes?
Yes, if they are heirloom or open-pollinated varieties. Most supermarket tomatoes are hybrids, so seeds from them will not produce plants identical to the parent. Check the label or ask the produce department what variety the tomatoes are before you save seeds.
What if my seeds get moldy during storage?
Mold during storage means moisture got into the envelope. Discard those seeds. To prevent this, make sure seeds are completely dry before storing them, use paper envelopes instead of plastic, and keep the storage area dry. If your home is very humid, store seeds in the refrigerator in an airtight container with a packet of silica gel or uncooked rice to absorb moisture.
Do I need to do anything special before planting saved seeds in spring?
No. Dried seeds stored properly do not need soaking or special treatment. Plant them in seed-starting mix indoors six to eight weeks before your last frost date, just as you would with store-bought seeds. They will sprout and grow normally.
How many seeds should I save from each tomato?
One ripe tomato produces hundreds of seeds, far more than you need for one season. Save seeds from three to five healthy tomatoes of the same variety to may support you have enough seeds and genetic diversity. This also protects you if some seeds fail to sprout.