Food Plants - AnnualSeeds

How to Save Tomato Seeds

Fully ripe disease-free tomatoes are the best candidates for seed saving. Seeds can be saved casually by squeezing them out onto a paper napkin and then air drying them, but fermentation is a better route.

Fermentation removes germination inhibitors and the gelatinous sheath from seeds, and it may treat some seed-borne diseases. Properly stored tomato seeds may remain viable for over six years.


Bucket of pulp from freshly crushed tomatoes waiting to be poured
into a smaller container to ferment for three days.

  1. Rinse tomatoes in water to remove dirt before harvesting seeds. Cut off open or damaged parts of fruit. We collect tomatoes in five gallon buckets then fill them with water. Cleaning any dirt off becomes a natural sweeping motion with your hands as you grab tomatoes from the water.

  2. Cut open ripe tomatoes one variety at a time and squeeze the pulp, juice and seeds into a container. If you have strong hands, you may crush the tomato in a five gallon bucket. Try to develop skill holding the tomato right side up and opening the tomato from the bottom blossom, and, with your fingers, then milking the germplasm gel which contains the seeds off the central column. This is the fastest method.
  3. Pour into a container with a lid. Do not add water as a substitute for tomato juice since dilution slows fermentation.
  4. Label and set aside the containers for three days at a temperature not more than 70°F (21°C).
  5. Stir the fermenting juices to submerge the pulpy material, once or twice daily. This prevents the build up of mold which is not harmful to the seeds but may discolor them.
  6. After three days decant. Pour into a larger container that allows you to add three or more times the volume of water and pour off the pulpy water but not the seeds at the bottom. Viable tomato seeds will sink. Repeat two or three times until seeds are clean. Note: not all viable seed varieties sink in water.

  7. If selling seeds commercially, soak clean seed in water with a cap of antibacterial bleach, 10% bleach solution, for 30 minutes to kill seed-borne disease. Then rinse seed under cold running water for seven minutes, constantly agitating and stirring the seed. This post-soak rinsing is needed to reduce total residual chlorine to below the National Organic Program (NOP) standard of four parts per million. Sanitize equipment thoroughly between uses to eliminate Late Blight contamination.
  8. Pour the seeds into a fine mesh sieve or window screen. Lightly spray off remaining gel or debris. If drying the seeds on a screen, spread out with water spray, not your hand. Wet tomato seeds will stick to your hand.

  9. Tap the strainer or rub your hand under it to remove excess water. Flip the strainer over, smacking it on a paper plate to deposit the seeds or allow seeds to dry on a screen.
  10. Label drying plate or screen with the variety name and date harvested.
  11. Let the seeds dry for five to six days at room temperature in a well-ventilated place.
    Stir and crumble seeds with your fingers daily to prevent them clumping together.
    As the seeds dry, lightly rub clumps together between your palms to separate
    seeds. We also rub dry seeds through a #2 cleaning screen .132 to separate
    remaining clumps before bagging, available from www.horizonherbs.com.
  12. Store in zip lock plastic bag in a cool, dark, dry place. Place label inside the bag. Refrigeration of seeds is not necessary but okay. Do not freeze seeds.


Bridget standing in front of some of the drying racks at Restoration Seeds.

21 Comments

  1. When pressed with time, we just squeeze a tomato on a paper towel, spread sticky jelly with seeds inside evenly, write name of variety on paper, date, hang the towel in the shade till bone dry. Store in small jar. Label jar. When planting time comes, cut a portion of paper with stored seeds. That’s our short version. We have seen people squash the tomato jell on a slice of bread to store….(not for consumption!) Thank you for sharing your comprehensive version,Chuck. Interesting article!

    1. Thanks for tip- I will try it! I AM pressed for time…
      let’s see if i can reproduce these heavenly organic cherry tomatoes.

  2. Chuck explains very clearly in 12 points how to do produce quality tomato seeds mostly free of seed borne diseases with the fermentation method. He also gives the quick method at the very beginning of his article. It is is for home use and the tomato variety has no obvious sign of disease(s), then the quick method is ok. For larger commercial or semi commercial tomato ventures then his method is best. And we need more farmers and gardeners selecting and producing quality seeds and marketing them as Locally Adapted Seeds (not in the EU as there are member countries of EU with a current legislation drawn from EU directives for seed all things). All the best Rick.

  3. I tried fermenting a fresh cherokee purple. Within two days in a dark room, the seeds sprouted. I will continue using the paper towel method.
    Dissapointed.

    1. I wonder if the seeds were too far mature inside the fruit at the time of harvesting. The comment below yours also sounds concerned about sprouting.

  4. I noticed a few seeds began to form a tiny bump of a taproot as a prelude to sprouting toward the end of fermentation. Will these still be viable when dried or should they be discarded?

  5. I am a gardener from an EU member country. I love tomatoes and every season I grow many varieties. I use this fermentation method to save seeds and I am delighted with the results. Every year I exchange seed with other gardeners in the US, Canada, and I have no trouble getting and sending seeds.

  6. Great information and rationale behind what’s being done. For smaller batches by the urban grower, I’ve been placing the fine mesh colander on top of a towel to absorb the water from the seeds before “wacking” it upside down on wax paper.

    Will try the sanitizing with the next batch.

  7. Hi everyone,
    I m delighted to have found so much good info here. I live in the Philippines and plan to grow cherry tomatoes of different varieties for testing first. Anyone has experience growing tomatoes from own seeds in the tropics?
    I may also be interested to purchase some (say 20 or so seeds) from anyone on this website, and would be fantastic ….
    Peter

  8. Thaniks, this is such a good and well illustrated description, exactly what I was looking for! I have a domestic setup, so used the paper towel method for my San Marzano seeds. Having discovered seeds sprouting inside ripe toms before, I’m sure they will be fine. I’m also going to try grafting onto vines from my F1 varieties when they mature; the idea of keeping viable tom plants over the winter appeals a lot.

  9. Accidental find while canning. Using a food mill with fresh tomato, the “trash” expelled (skin, seed, etc.) was filled with separated tomato seed and no juice. (we run through mill 3 times to get as much juice as possible into sauce.) A hot water rinse under the kitchen faucet several times in a screen basket dissolved and rinsed off the gel. Picking the best, disease free samples to use for seed would likely not have anything to pass on.

  10. I have a favorite tomato that still has green healthy fruit on it as of 1/5/2019. I can’t believe it! It’s near the end as we just had a cold week here in NoCal so I’m concerned it’s not going to get any more ripe. I’d love to save the seeds from this variety. It produced great fruit and was very disease resistant versus my other plants. Any guidance on whether I’ll be able to dry seeds from green tomato? Thanks!

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