Can You Harvest Seeds From Store-bought Tomatoes?

Tomate de supermarché avec émoji douteux, semences de tomate dans une main

Ill.:, &, montage:

Question: Can I collect seeds from the tomatoes I buy in the supermarket and use them to grow my own tomatoes?

Thomas Ng

Answer: Yes, you can, but it might not be the best idea.

F1 tomatoes are identical; F2 tomatoes are variable.
All sorts of unexpected traits can show up in the second generation (F2) when you sow the seeds of a supermarket tomato (F1). Photo: & Simply Fresh Fruit

Most tomatoes grown in supermarkets are F1 (first filial) hybrids, that is, are developed from a controlled cross between two different tomato lines. This is done because such hybrids often combine a host of desirable traits—better disease-resistance, faster growth, better shelf life, more even ripening, etc.—, plus they also have “hybrid vigor,” sort of a special mysterious and never fully explained shot of productivity that comes from crossing two unrelated strains. However, tomatoes grown from seed collected from an F1 hybrid (the supermarket tomato) result from the tomato flower crossing with itself and will be F2 (2nd filial or second generation) hybrids, showing a variable mix of traits—and not necessarily the best ones!—from the two parent lines and will no longer demonstrate hybrid vigor. Indeed, the resulting fruits can come in all shapes, sizes, colors and tastes.

Also, supermarket tomatoes were developed for good shelf life (that’s good) and the ability to travel well … not so desirable in a home garden tomato. Supermarket tomatoes often have a tough skin and rather hard texture, suitable to shipping long distances. That’s pretty much the opposite of the tomato you’ll probably want for your garden: a juicy, softer skinned tomato that melts in your mouth. And supermarket tomatoes are rarely chosen for their taste: in fact, many have a gene for uniform ripening that only comes at the cost of reduced taste. People have long complained that supermarket tomatoes are bland and flavorless: now you know why. I suspect you’d prefer delicious over bland.

Finally, supermarket tomatoes are usually developed for either greenhouse growing or, if purchased in winter, growing outdoors in a tropical climate not likely much like yours. So, they may not grow or mature well under your very different growing conditions.

Heirloom Supermarket Tomatoes

Mystery heirloom tomatoes in a plastic pack.
Supermarket heirloom tomatoes: yes, they’ll breed true, but true to what, exactly? You know nothing about them. Photo:

That said, some supermarkets do offer heirloom varieties of tomatoes. Not usually named varieties (the Fruit and Vegetable Department manager in my local supermarket mockingly calls them “mystery heirlooms”), but still. Heirloom tomatoes are not hybrids, but rather stable, non-hybrid varieties that will be true to type (“breed true”): that is, will give essentially identical tomatoes in the next generation … and each generation after that. They were usually chosen for better taste, among other criteria, and certainly not for adaptability to shipping. But if your tomato patch is practically right outside your back door, is that really a problem?

Even if you do find an heirloom tomato to use for seed, however, you still don’t know much about it. Is it determinate, requiring little staking, or indeterminate, with a tall stem needing major staking or a tomato cage? Is it an early tomato or a late one? Maybe too late for your short-season climate? You can’t tell that just by looking at a mystery heirloom tomato. That’s the kind of information you only get if buy a pack of tomato seeds with a description of the variety on the label.

How to Harvest Seed

So, whether you’re willing to risk sowing a regular supermarket tomato or you’ve found an heirloom tomato to start with, you’ve decided to harvest its seeds. Fine. Now you need to know how to do it. Not that it’s particularly complicated, but harvesting seed from a moist fruit like a tomato is a bit different than from a dry seed capsule like a poppy, a radish or zinnia.

You could simply scoop seeds out of the fruit, clean them roughly with a paper towel and let them air dry overnight before sowing, but you’ll get better results if you allow the gelatinous sheath surrounding the seed to decompose first. This is called fermentation. This step removes germination inhibitors, leading to faster and better germination and early growth. There is also some indication fermentation might also help prevent certain seed-borne diseases.

Here’s how to go about it.

  1. Cut the tomato open. 
Spoon scooping seeds from red tomato.
To harvest, just scoop some seeds out of the cut tomato.
  1. You’ll see numerous seeds surrounded by pulp in the cavities of the fruit. With a spoon, scoop out enough to meet your needs.
  2. Drop the seeds and pulp into a glass, jar or small bowl.
  3. Add enough water to cover well.
  4. You can cover the container with a cloth or paper towel to keep odors in (you did understand there would be fermentation, didn’t you?) and fruit flies out.
  5. Place the container in a warm spot where fermentation will occur. 
Tomato seeds fermenting in a glass jar.
During fermentation, the seeds will sink to the bottom and mold will form on top. Photo: Rural Sprout
  1. Over the next few days, probably about 3 to 5, the pulp will start to decompose and the seeds will begin to separate out, sinking to the bottom. Solids will rise and brown or white mold with a slightly unpleasant odor will form on the top. In between there’ll layer of watery, translucent liquid.
Remove the mold with a fork. Photo: The Spruce
  1. When the mold pretty much covers the surface, the seeds will be ready. Remove the mold with a fork.
  2. Add water and stir or shake, then let settle for a few minutes. 
  3. The good seeds will sink to the bottom, so you can then carefully pour off the excess liquids and solids on top. (They can go into the compost pile.)
Rinsing tomato seeds in a kitchen sieve.
Clean the seeds in a colander. Photo: The Spruce
  1. Pour the seeds into a colander and rinse with running water to clean them. Carefully rub the seeds against the mesh to remove any sticky remnants or remove any bits of pulp or mold by hand. 
Tomato seeds drying on a plate.
Dry the seeds before storing them. Photo:
  1. Spread the seeds on a smooth surface – a plate, wax paper, a tray, etc. – so they can dry and set in a warm, dry spot.
  2. Shuffle the seeds lightly with your fingers every day so they can dry evenly and to keep them from clumping together.
  3. When they’re thoroughly dry, you can store the seeds in a paper envelope or a pill bottle until it’s time to sow them. They’ll keep for 3 to 4 years, even more if you keep them cool. 

Sowing Tomato Seeds

Tomato seedlings in peat pots.
When it’s time to sow the seeds you harvested, just follow the instructions given here. Photo:

When it comes to actually sowing your supermarket tomato seeds, first make sure it is the right time of the year (the number one error beginning gardeners make with growing tomatoes from seed is starting them too early!), usually 6 to 8 weeks before the last frost date in your area, then follow the steps in the article Grow your own tomatoes from seed: a guide for beginners.

So, can you harvest seeds from store-bought tomatoes? Sure. Should you? Well, that’s up to you to decide, but personally, I prefer to know the tomato varieties I sow, so I always start with purchased or exchanged seed from a reliable source that offers a complete description.

Larry Hodgson is one of Canada’s best-known garden communicators. He has notably been editor-in-chief of HousePlant Magazine, Fleurs, Plantes et Jardins, À Fleur de Pot and Houseplant Forum magazines and is currently the garden correspondent for Le Soleil and radio garden commentator for CKIA-FM Radio. He has written for many garden publications in both the United States and Canada, including Canadian Gardening, Harrowsmith, Horticulture, Fine Gardening and Organic Gardening. He also speaks frequently to horticultural groups throughout Canada and the U.S. His book credits include The Garden Lover’s Guide to Canada, Complete Guide to Houseplants, Making the Most of Shade, Perennials for Every Purpose, Annuals for Every Purpose, and Houseplants for Dummies, as well as nearly 60 other titles in English and French. He is a past president of the Garden Writers Association (now Garden Communicators International) and the winner of the prestigious 2006 Garden Media Promoter Award offered by the Perennial Plant Association. He resides in Quebec City, Quebec, Canada.

4 comments on “Can You Harvest Seeds From Store-bought Tomatoes?

  1. re Harvest seeds….. I have a number of heirloom picked up over the years, and harvest the seeds each year to have a “fresh” supply. you outline pretty much what I do, but I would add a warning to step 12. NEVER put on a paper towel to dry. they stick, and have to re soak the whole towel to separate (so seeds are wet again!) made that mistake more than once.

  2. I have had store bought tomato seeds come up, make normal size to fruit.

  3. Other vegetables can be even stranger from seed. However, some of the supermarket squash are more stable from seed than those grown in the garden. They grow on farms with a whole bunch of the same sort that happily pollinate each other. In home gardens, they hybridize with squash that do not even seem to be closely related. I think you wrote about that earlier.

Leave a Reply

Sign up for the Laidback Gardener blog and receive articles in your inbox every morning!

%d bloggers like this: