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How To Save Tomato Seeds

A fast, easy way to grow next year's tomatoes!

Saving seed is always an interesting project. It's fast and easy to do, and when the weather becomes ideal, you get to plant the saved seed, making it that much more satisfying to see the new crop springing to life.

Most of the time saving seed is no more than collecting it and then storing it in airtight containers with some silica pouches to keep the seed dry.

Tomato seeds, however, are a little different. In fact any seed that is enclosed in fleshy pulp, like tomatoes, melons, or cucumbers, needs to go through a fermentation process to separate the pulp from the seed before they can be dried and saved.

No worries though. It's super easy to do and takes about 10 minutes of time, and since tomatoes are definitely one of the favorite plants to grow in the garden, you'll get a kick out of growing next year's tomatoes from this year's plants.

First - A Word About Hybrids

It should first be mentioned, that any plants grown from seeds of hybrid tomatoes will not come true to type, meaning, they will not resemble the plants they came from.

Since hybrid seed is created by crossing two highly inbred parent plants, the result is F1 hybrid seed (like 'Early Girl'), which can only be recreated if the exact same two parents are bred again.

Don't let this discourage you from saving seeds and doing your own tests with hybrids. You just might come up with a really great new tomato growing seeds from hybrids, and that is what makes saving seed so interesting!

How To Tell If It's a Hybrid

You will always easily know if the plants you have are hybrids because every plant and seed packet is marked on its label. So look for verbiage that says "F1 Hybrid."

Non-Hybrid Tomato Seed

Any tomato that is not marked as an F1 hybrid, and there are tons of them, will come true to type and you will get a plant similar to the parent plant.

These tomatoes include heirloom and open pollinated tomatoes.

In fact, many gardeners consider open pollinated plants to be stronger since they have developed in a natural environment, and as such, are better acclimated to the growing area around them.

OK - so enough of that - now go get some tomatoes, and let's get started!

F1 Hybrid 'New Girl'

Heirloom or Open Pollinated 'Yellow Pear'

Remove The Seeds From The Fruit

As mentioned in the introduction, any seed that is in enclosed in fleshy pulp needs to have the pulp separated from the seed before it can be dried and stored. The following steps will show you how.

1. Slice the tomato down the middle

2. With a spoon, scoop out the seeds and pulp

3. Put them in a clean, wide-mouthed, glass jar like a peanut butter or mayonnaise jar that has a top

Slice the tomato
down the middle

Scoop out the
seeds and pulp

Place in a clean jar

Start The Fermentation Process

1. Add about 1/4 cup (60 ml) of water to the jar

2. Put the lid on and let the jar sit in an out of the way place for a few days at room temperature or higher. 80 to 90° F (27 to 32° C) temperature is ideal, but not necessary

Note: Where I live, we are having a super cool summer. The house has not gotten above 60° F (16° C). So the process took a bit longer, but it worked.

Add water

Put on lid and let sit

Stir and Watch

1. Remove the lid and stir the seed and water mixture once or twice a day

2. Now three things can happen to let you know that your seeds are done:

  • Bubbles will start to rise

  • Most of the seeds will settle to the bottom

  • A dense layer of mold will develop

Note: This fermentation can take anywhere from 2 to 7 days. The warmer your house, the faster they will ferment.

Since my house was so cool, after about 6 days I had bubbles rising and the tomato seeds had settled nicely, but I never had mold grow.

So pay attention you may have only one or all three fermentation processes happen.

Stir once or twice a day

Check for signs of
fermentation. In this case,
I had bubbles and the
seeds had clearly settled

Stop The Fermentation Process and Skim

1. When you see signs of fermentation, stop it by adding enough water to double the mixture in the jar (see note below)

2. After the water has been added, stir well

3. Notice that good seeds will sink to the bottom, and pulp and debris will stay near the top

4. Using a spoon, skim off the debris on top. Keep stirring and skimming until only the good seeds are left

Note: As soon as you see a good fermentation process going, you will want to stop it. When fermenting seeds, try to be a bit careful that you don't let your seeds ferment too long.

All we are trying to do is separate the seeds from the pulp. Once the pulp has separated from the seed, the chemical that was in the pulp that inhibits germination is now gone.

The warm, wet conditions in the jar after fermentation are perfect for sprouting seed, so don't let your seeds ferment too long or else they will start sprouting.

Add enough water to
double the mixture

Stir and skim

Rinse and Dry

1. When you have only the good seeds left, rinse them in a sieve and place them on a paper towel, fine-mesh wire screen, or a dish to dry

2. Never dry your seeds in direct sunlight or the oven! Monitor the temperature and make sure it does not go above 95° F (35° C), that is too hot.

Note: Using a paper towel to dry your seeds saves time.

Spread the cleaned seeds as evenly as you can over the paper towel. The dried seeds will stick to the paper.

When the seeds are dry, just roll up the paper towel and store until spring.

At planting time, unroll the towel. You can either place the entire towel on a flat of seed-starting mix and cover it lightly with perlite, or you can cut the paper towel up and plant the seeds a few at a time in pots or directly into your garden.

Basically you have made your own seed tape. As the paper towel breaks down, the seeds sprout, and if you spaced them well on the paper towel, you won't have to thin the seedlings.

Rinse and dry

How To Tell When Seed Is Dry

1. Dry your seeds for about one week

2. When the seed is hard enough that you can't bite into it, or smash it, then the seed is dry enough to store

3. Store your seeds in an airtight container, preferably one with a rubber gasket like a baby food jar, as soon as possible so they won't reabsorb moisture. You can also add small pouches of silica gel, which are available at craft stores to help absorb any moisture. For more, read our saving seeds story

4. Keep your seeds in a cool, dry place, around 32 to 41° F (32 to 5° C) until you are ready to plant them

5. Finally don't forget to label your seeds, so you know what they are!

Clean, dry seed


You can do the above technique for many plants that have seeds in fleshy fruit such as magnolias, melons, and cucumbers, and that is good to know.

But, the really interesting thing you will notice is that in only a year or two, if you save seed for several years, that each year the plants will do better and better.

This is because you will have seed from plants that are adapting to your area and climate and are passing those traits on to the next generation through their seed!

Link to continuing article, How To Save Annual Flower Seeds is below.

Link: How to Save Annual Flower Seeds

The writer is a member of the National Garden Writers Association, a nationally published writer, and a certified organic grower. She regularly speaks and writes about all gardening related topics, with an emphasis on making gardening a successful and enjoyable process for anyone who wants to learn. Weekend Gardener Monthly Web Magazine concentrates of giving detailed gardening tips and gardening advice to all levels of gardeners.

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