Heirloom Tomatoes

Saving Heirloom Tomato Seeds

Forget seed catalogs, I’m shopping for my tomatoes at the farmer’s market. Walking through the colorful displays of produce at my local farmer’s market, I’m brimming with anticipation for the next gardening year. The heirloom tomatoes that I pick out today—given they pass the all-important taste test—will be the garden bounty of my future.How to Save Heirloom Tomato Seeds (it's a thing...)

Saving heirloom tomato seeds brings back those memories of science classes: beakers and safety goggles, anticipation and disgust, curiosity and pride. The seeds can’t be just scooped out and dried; they need to be removed with all the slimy tomato guts and left to ferment. The gross factor of fermenting these tiny seeds is about as fun of a science experiment as you can get, making it an ideal project to do with kids.

Related: Getting Back to Basics with Seed Saving

Now you may be asking yourself, “Why on earth do I need to ferment the seeds? Can’t I just scrape them onto a paper towel and dry them?!” The answer is that fermenting the seeds is copying the natural process the tomatoes would go through to reproduce. The membrane around the seeds prevents germination and can carry disease. By fermenting it, it sterilizes the seeds and thus protects the next year’s plants.  In addition, it  gets them ready for winter storage so they will be primed for good germination rates when the time comes.

Here is What You’ll Need:

1. Choose Your Seeds

The most important part of saving heirloom seeds is selecting the best fruit to begin with. Whether you are purchasing your tomatoes or have grown your own, you should look for the best visual example of a variety: perfect color, size, and shape. Ensure there is no disease or pest damage visible, and don’t forget to taste them. Yummy tomatoes make seeds that make yummy tomatoes.

German Strawberry Tomato

2. Scoop Out the Guts

Gently cut your perfect tomato into sections. Grab a spoon and scoop out the seeds and the gel-like membrane that they are surrounded by. This whole glob goes right into the Mason jar so it’s going to get a bit messy. Fill up each jar with about ¼ cup to ½ cup water, just enough to cover the goop.

Saving Heirloom Tomato Seeds

3. Cover and Label

Write the variety name on a piece of paper towel folded square, and secure to the lid by screwing on the ring over top. This allows for air to circulate to the mixture as it ferments, but also makes sure you don’t forget the variety.

4. Store in a Warm Place

Now set the Mason jars someplace warm, out of direct sunlight where they won’t be disturbed for a few days. Depending on the temperature, it could take 2 days to a week so be prepared to stick around and keep an eye on them.

 5. Check for Mold (You Want Mold)

Within a few days, the top of the liquid should have a grayish rim of scum and even later, a full cover of mold.  At this point the seeds should have sunk to the bottom of the muck as well. Congratulations! This means that the fermentation process is complete. This is also great news because the jars are likely smelling quite awful by now.


 6. Strain and Rinse

Add another ½ cup or so of water to the jars to dilute the gunk and allow the viable seeds to sink to the bottom. Gently pour off the top layer of fermenty-goodness and then strain the seed into a fine-mesh sieve.

How to Save Heirloom Tomato Seeds

 7. Drying

Place the strained seeds on a plate or bowl and set back in the warm dry place for a few days to dry out.  Many people use paper plates, but my little glass bowls work just fine for me. Make sure that you attach or set your paper towel cover / label to the seeds – there is nothing worse than going through the process of fermenting seeds and then forgetting which variety they are!

 8. Storing

Once your seeds are dry, you can shuffle them into some handy little coin envelopes, label them up, and store in a cool dry place until next spring. You have graduated from science-class geek to a true heirloom-tomato alumnus.

What’s an Heirloom?

Heirloom seeds have been saved and passed on for many generations and so the plant, flowers, and fruit are true to type of the original great-great-great-(insert 50 years here)-grandmother plant. The seeds have been saved for their outstanding qualities, be it beauty, flavor, and yield, or disease, pest, and weather resistance. Heirloom vegetables and fruits provide much diversity from the standard fare mass-produced by industrial food production.

There are many colorful and unique tomato varieties, but beauty and diversity doesn’t mean it’s an heirloom. Hybrid tomatoes have been created by cross-pollinating strong characteristics of different varieties, making brand-spanking new varieties. While the tomatoes can look and taste as good as heirlooms, saving these seeds comes with problems.

Some seed companies create franken-fruits that only contain sterile seeds, ensuring that you always have to buy from them.  Even if you could save and germinate the hybrids, there is no guarantee what characteristics the new plant will have. Remember, they cross-pollinated before so who knows what they will get up to with the other tomatoes, nor what the offspring will be.

Hey! Now that you have your tomato seeds ready, how about some printable seed envelopes? Download them here:

Free Printable Vegetable Seed Envelopes from Garden Therapy

About the Author : Stephanie Rose

A city girl who learned to garden and it changed everything. Author, artist, Master Gardener. Better living through plants.

View all posts by Stephanie Rose

  1. Evalyn
    EvalynAugust 10,12

    Please continue with how to save other seeds. Lettuce, radishes, squash, etc. Some seem obvious, but what others like tomatoes, need a special process? GMO is scaring the life out of me, I need to be able to fight back somehow.

    Thanks for this.

  2. Stevie
    StevieAugust 10,12

    Evalyn, great suggestion. I’ll work on some follow up posts on seed saving.

  3. Mark Willis
    Mark WillisAugust 13,12

    I know that following the fermentation process you describe is uspposed to remove the anti-germination stuff surrounding the seeds, but can you please explain why when I put rotten tomato fruits in my compost bin I still get loads of volunteer tomato plants next year in the places where I use the finished compost? Is it really necessary to do the fermentation thing? Why not just dry the seeds, gunk and all?

  4. Jane @ Cottage at the Crossroads
    Jane @ Cottage at the CrossroadsAugust 13,12

    Hello! Thanks so much for posting how to save the heirloom tomato seeds. I have some outstanding purple cherokees i the garden right now. They are the best tasting tomato that I’ve ever had, so it’s good to know how to save the seeds.

  5. maryhysong
    maryhysongAugust 13,12

    the fermentation process also helps control some seed borne diseases. @Mark Willis, because the fruit fermented in the compost. You could dry them out, but in most climates it would be hard to get all the gel around the seeds dried out before it got moldy.

  6. Lisa and Robb
    Lisa and RobbAugust 14,12

    The compost question is interesting.

  7. Jenny
    JennyAugust 14,12

    Yup, that’s what I’ve been doing with the seeds of the varieties that I like so far.

  8. Liz
    LizAugust 14,12

    I source some of my chilli seeds from farmer market fruits too – its always fun trying work out which variety I’m growing.

  9. diary of a tomato
    diary of a tomatoAugust 14,12

    The best part of sourcing tomato seeds from ones bought at the farmers’ market is knowing that they’ve adapted to your zone! We don’t ferment, we simply select prime specimens, squeeze the seeds out onto heavy paper, label and let dry. They don’t store as long as the fermented ones, but are fine if you replant every year.

  10. Stevie
    StevieAugust 14,12

    Mark, the tomatoes natural reproduction process is to fall off the plant and rot, fermenting the gel sack surrounding the seeds which acts as a germination inhibitor when the fruit is on the vine. This same thing will happen in your compost as the tomato rots, leaving seeds primed for germination.

    If your compost doesn’t get hot enough, then seeds will not be killed off and that’s why you will get tomato (and squash and potato and weed) volunteers.

    As Maryhysong pointed out the volunteers will have properly fermented and thus destroying the disease that is carried in them. With Late Blight being such an issue here, I never put any tomato bits at all in my compost (as mine doesn’t get hot enough to kill disease) and I always ferment the seeds from the farmers market.

    I hope this helps!

  11. Jen
    JenAugust 15,12

    Thanks for the heads up. We grew Cherokee Purple heirlooms this year and work a community garden that grew quite a few heirlooms. We are going to give seed saving a try.

  12. Yael from Home Garden Diggers
    Yael from Home Garden DiggersAugust 15,12

    How interesting about the need to ferment the seeds. I never knew about this. I have never tried saving tomato seeds, but I get plent of volunteers either from fruit that fell to the ground or those that ended up in the compost bin. Great post.

    Yael from Home Garden Diggers

  13. Andrea
    AndreaAugust 16,12

    Great post Stevie, i now know why my seeds didn’t germinate i didn’t let them ferment for long enough. This year I’m buying my seedlings direct from our local organic veggie garden so hopefully i can try saving some seeds next year.

  14. Sheila
    SheilaAugust 16,12

    Has anyone else ever grown “Mortgage Lifter” tomatoes? They are the best I’ve ever tasted, but the seedlings are hard to find. Thanks for this information.

  15. Annie
    AnnieAugust 23,12

    I needed to know about this. Thanks for sharing:)

  16. Sarie
    SarieAugust 26,12

    Thanks. I will do this however I buy heirloom tomato plants in the spring but always get a lot of plants from my composted seeds from the year before. Your way will probably work better and I will know what I am growing!

  17. Melanie
    MelanieSeptember 3,12

    Thanks for this. I have my eye on some big tomatoes that I’ve ear marked for fermenting.

  18. Andrew
    AndrewFebruary 15,13

    I’ve never heard of fermenting seeds, but it does make perfect sense. Thanks for the tips.

  19. Nancy
    NancyNovember 16,13

    How soon after the seeds are dry can I plant in a container inside the house? I am new to this so I also need to know planting directions and approximately how long will it take to sprout.


  20. Frank Mosher
    Frank MosherAugust 19,15

    Just for the record, almost all tomatoes available at the supermarket, are identically reproduceable from their seeds, in particular, all the “grape” varieties, even thou some are hybrids – they still come true. Great blog!

  21. Seminte de Rosii
    Seminte de RosiiOctober 9,17

    I save seeds only from “open pollinated” (OP) or heirloom tomatoes, because these are tomato varieties are true to their type from their own seed, which means the next season’s new plants will maintain the same characteristics as the previous one.

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