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How to Harvest and Save Tomato Seeds

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Gardeners love to order seeds, and I am no exception. But if 2020 taught us anything, it’s that seeds can sometimes be a scarce commodity, and that should waken us up to the fact that we need to develop our seed saving skills. Learning how to save tomato seeds is an easy way to begin your own seed bank, and I’ll walk you through the easy steps to do it.

Cut tomatoes with seeds shown

As I’ve tried to be more mindful of what I truly need, this has translated into using what I already have and trying to save the seed varieties I thoroughly enjoy. Seeds from my very own garden is a great start to being less wasteful and more self-sufficient. Saving tomato seeds from heirloom tomatoes is super quick and easy and a great way to get started with seed saving.

Why save garden seeds?

One of the more expensive parts of planting a garden each year can be buying seeds and plants. This can be especially true if you prefer heirloom varieties or organic seeds. But if you have a little patience and a spare jar, you can easily save your own seeds from a variety of plants. Just be sure you have a good system in place for organizing your seeds. (See my full post on seed organization.)

Another note about saving your own tomato seeds is you want to avoid saving seeds from hybrid tomatoes if possible. Not that hybrid tomatoes don’t taste delicious or have their place in the home garden, but hybrids are developed to have certain qualities. 

When hybrid seeds are saved and replanted the next season, they should germinate and grow, just like an heirloom seed, but they may not have the same qualities as the fruit from the parent plant. Heirloom tomato seeds are generally the tomato plants I look to when I’m deciding which variety to save for the next year. 

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When to Save Tomato Seeds

If you’re planning to harvest tomato seeds, the best time to do it is when the tomatoes are fully ripe. Ripe fruit will start coming off of the plants mid to late summer and into the fall. And just one tomato can give you more than 100 seeds, way more than you’d get in any seed packet from the garden center. 

Be sure to avoid using under ripe tomatoes for your seed saving, since the seeds within may also not be fully developed yet. You want all the viable seeds you can get! Though it’s probably understood, you also want to avoid saving seeds from any plant that is diseased; choose a strong plant for the best seeds.

Fermenting Tomato Seeds

While you might think of saving tomato seeds as just scooping them out and drying them off, there’s actually another step. If you’ve never noticed before, tomato seeds have a gelatinous coating around each seed and this has to come off before you can save them. 

​You’ll notice in the steps below that one step involves just letting the freshly scooped seeds sit in a jar of water for a few days. This fermentation period is what works that gel from around the tiny seeds you’re trying to save. While you’re not making sauerkraut, you may notice a pungent smell when you open the jar. This is normal! Now, here’s what you’ll need to get started. 

Seed Saving Supplies and Resources

The supplies for saving tomato seeds at home is pretty simple, so don’t over think it. Most of these items you’ll have on hand in your day to day kitchen. 

  • Ripe tomato (if saving a small variety like a grape or cherry tomato, then use at least 2.)
  • Glass jar (mason jar or baby food jar)
  • Water
  • Rubber band
  • Cheesecloth or coffee filter
  • Paper Towels
  • Paper Envelopes (or a cool, dry place to store your seeds)

Have your supplies out and ready when you’re ready to begin saving your seeds.

Tomato Seed saving step-by-step

Now that you have one of your best tomatoes, as well as your other seed saving supplies, it’s time to start harvesting tomato seeds!

  1. The first step is to cut open the ripe tomato, and gently squeeze or scoop out the seeds and pulp into a clear jar. (You can still use the rest of the tomato to eat, so don’t waste it.)
open tomato with seeds
cut tomato with seeds shown
  1. Add an inch of water above the seeds and pulp and cover the jar with cheesecloth or a coffee filter. Keep jar in a warm place around 70 degrees (easy to do in your house in the summer). 
seeds and pulp
seeds and pulp in jar
  1. Over the course of two or three days, gently swirl the water in the jar several times a day (this is when the fermenting process!). A slight layer of mold may form during this time, but this is normal and helping to break down the gel. You will notice that the pulp releases from the seeds, and they settle to the bottom of the jar.
tomato seeds in water
seeds and water in jar
  1. Drain water out of jar using a fine mesh strainer. Spread seeds onto a paper towel. Allow to dry completely. 
  2. Store in an envelope. (I use simple mail envelopes.) Don’t forget to label the envelope, so you know what variety of tomato seed you’ve saved, especially if you’re saving more than one kind. 
  3. Keep seeds in a cool, dry place until you’re ready to plant your seeds in the spring!
seeds on towel
Saved tomato seeds drying on paper towels

More Seed Saving Information

Want to keep going on your seed saving adventure? Check out these helpful resources!

  • The Seed Garden: The Art and Practice of Seed SavingFilled with advice for the home gardener and the more seasoned horticulturist alike, The Seed Garden: The Art and Practice of Seed Saving provides straightforward instruction on collecting seed that is true-to-type and ready for sowing in next year’s garden
  • The Seed Saving Bible: The goal of this book is straightforward: To guide you through the intricate world of seed saving, ensuring you’re well-prepared to tackle any challenge that comes your way.
  • Preserving Your Own Seeds for your Garden: This book was developed to help any individual who is seeking to start preserving their own seeds for future use and growing. You will learn everything you need to know to effectively grow and preserve seeds. 
  • Saving Seed Article from the NC State Cooperative ExtensionA good next step if you’re looking for more general information on seed saving is this simple article that can apply to all home gardeners. Find out what seeds from your spring, summer, and fall gardens can and should be saved. A great read before the end of the season. 

Storing Saved Seeds

Be sure you’re storing all of your seeds, whether saved by you or leftover from last season, in a cool, dry place. Moisture is the enemy of seeds if you’re looking to save them. Check out my full post on Seed Saving Ideas for Gardeners with great systems to save and keep your seeds organized. 

Some seeds can also be saved in the freezer. I don’t personally freeze my seeds, but if you’d like more information on that, check out this article from Colorado State University. As gardeners, we’re always learning and growing! Pun intended.

And that’s all there is to it. Saving seeds was not a new concept to our grand parents and great grandparents, but it seems to be less common these days. As a home gardener, save those dollars you’d be spending on a new package of seeds and instead use what’s growing in your very own garden.This is a wonderful way to pass heirloom seeds down to family members and friends for years to come! You’ll be glad you started saving seeds. 

Have another way to save tomato seeds? Let us know in the comments below!

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