How To Save Tomato Seeds For Planting Next Year

One of the joys of gardening is simply witnessing the natural process of plant life. For tomatoes, the natural job of the fruit is to spread and sow seeds (and feed hungry animals). Today, I’ll explain how to save tomato seeds for storing and planting later.

This topic is for gardeners who plan to grow the same plant varieties, year after year. There is nothing wrong with this! If you find a type of tomato that suites your needs, you may never have to buy seeds again.

In this article, I’ll go through how to harvest, ferment and dry tomato seeds. I’ll also share some tips to ensure those seeds remain viable for as long as possible.

Dried tomato seeds
Saving tomato seeds.

1. Choose Fully Ripe Tomatoes

The first step to successfully saving tomato seeds is to choose fully-ripened tomatoes. This is a crucial step! The viability of seeds increases when a fruit is allowed to fully mature on the plant.

Also, choose tomatoes that exhibit traits that you find desirable. For example, you may choose to save tomato seeds from a large tomato with a shape you like.

Red tomato on cutting board
Fully-ripened tomato.

The reason for doing this is that genetics are at play. Saving seeds from beautiful, healthy-looking tomatoes will increase the chances of passing down those characteristics to the next plant.

Cross Pollination

If you grow multiple tomato varieties in the same garden, you may want to skip ahead and read more about cross-pollination. Basically, two heirloom tomato varieties may cross pollinate during a grow season.

This can result in your saved seeds containing 50/50 hybrid genetics from two different plant varieties. To try to avoid this, you can isolate flowers during the pollination/fertilization period. This will keep insects from bringing unwanted pollen to your tomato plant’s flowers.

However, if you only grow one tomato variety, this is nothing to worry about! Since just one set of genetics is present, the plant won’t have a source of alternate pollen nearby.


2. Remove Seeds

Fresh tomatoes can contain up to 95% water, meaning they are healthy and hydrating, but also a mess. For removing seeds, I recommend using a large cutting board, or even working outdoors with some newspaper for easy cleanup.

How To Remove Tomato Seeds (Steps)

Tomatoes store their seeds in vertical chambers, so the best method is to slice the tomatoes lengthwise. I usually cut the fruits into 6 pieces for easy access to the seeds.

The seeds are suspended in a thick liquid, but will come loose with just bit of encouragement.

Steps:

  • Wash and dry the tomatoes.
  • Set up a large cutting board and a glass or ceramic jar.
  • Slice tomatoes lengthwise into 6 sections. Large tomatoes are best dealt with in several pieces. If you are growing cherry or grape tomatoes, simply slice them in half lengthwise. Always use a good tomato knife to get through tough skins!
  • Use your finger or a spoon to remove seeds. Using gloves if desired, remove the seeds into the jar by gently scraping them from the tomato. Tomato seeds should will free easily. Try squeezing the tomato to release some of the water content into the jar along with the seeds.
  • Begin fermenting seeds (next section).

Once you have enough seeds removed from the tomato, you are ready to start the important process of fermentation.


3. Add Water and Ferment Seeds

Fresh tomato seeds are encased in a gelatinous sac. This substance prevents germination while the seeds are within the fruits, and protects the seeds from being digested by animals. In nature, this allows tomato seeds to be spread by tomato-loving critters through their droppings.

When an animal eats a tomato, the seeds pass through the digestive tract, fermenting along the way. This naturally removes the inhibiting gel, and when the seeds come out, they are ready to germinate.

Fresh tomato seeds closeup
Gel sac surrounding fresh tomato seeds.

Without removing the gel from your tomato seeds, they may have a low germination rate when you go to plant them. To avoid this problem, you can easily mimic nature and ferment the seeds in water.

How To Ferment Tomato Seeds (Steps)

Fermentation is completely natural and very easy. Basically, you place the tomato seeds in a jar, add fresh water, cover loosely with a paper towel or coffee filter, and let sit at room temperature for a few days.

Steps:

  • Place the seeds in a small jar. Use a glass jar or ceramic container (avoid metal). Make sure the lid lip is small enough to fit a rubber band around it.
  • Cover the seeds with water. Use water to submerge the seeds. I usually just fill the jar to within 1 inch of the lid.
  • Stir to release any air bubbles. Using a clean spoon, stir to release air pockets around the seeds. The goal is to have as many of the seeds sink to the bottom as possible.
  • Cover with a paper towel. You can also use a coffee filter or any breathable material. Aeration is important, so don’t use an air-tight seal. Keep the paper in place with a rubber band around the lid of the jar.
  • Place in a room temperature location. Place the jar and seeds in a dimly-lit location that isn’t too warm (around 70°F is ideal). After this is set up, you simply wait for the natural fermentation process to begin.
Fermenting tomato seeds in glass jar
Tomato seeds fermenting at room temperature.

How Long To Ferment Tomato Seeds?

Once you have set up your jars, the fermentation process will begin. The goal of fermentation is to just remove the germination inhibiting gel sac from the seeds.

Simply put, tomato seeds should be fermented for 2-3 days at normal room temperature before drying and storing. If your home is warmer, the process may go faster. Inspect the fermenting seeds daily with a clean spoon to avoid seeds beginning germination or turning brown.

Fermenting tomato seeds in jar
Tomato seeds fermenting.

Seeds that ferment for too long may begin to germinate in the water solution. Over-fermented seeds may also have a lower germination rate. 2-3 days at room temp is plenty of time to properly remove the gel sacs and prepare the seeds for drying.

Can I Dry Tomato Seeds Without Fermenting?

Tomato seeds will dehydrate without fermenting. However, the germination inhibiting gel will not be broken down, potentially leading to poor sprouting rates.

Basically, drying tomato seeds without fermenting is possible, but may lead to lower germination rates. The gel sac surrounding each seed is broken down during fermentation, leading to better viability in the long run.

If you plan to dry tomato seed without fermenting, try rubbing the seeds on an abrasive surface (like a fine-mesh strainer or paper towel). This can help break up the seed’s gel sac, allowing for faster drying and better germination later on.

Fermentation may sound intimidating, but the process is incredibly simple. It just requires a few days of waiting!


4. Strain and Dry Seeds for 2-3 Days

After your tomato seeds have fermented for 2-3 days, they are now ready to be dried. Thoroughly drying the seeds is critical for long term shelf life.

First, using a spoon, remove any seeds that are floating on the surface of the water. These seeds will likely have low germination rates. This is not completely necessary (if you have limited seeds, for example), but will help ensure better sprouting rates from your supply.

Strain the remaining tomato seeds from the water with a fine mesh strainer. Run the seeds under cool water and remove any bits of tomato flesh from the seeds.

Lay the seeds out on a paper or ceramic plate and place it in a well-ventilated area of your home. If you want, you can face a small fan on the lowest setting towards the seeds to speed up the drying process.

Agitate the seeds once or twice a day to encourage them to flip over and dry evenly.

Note: If it is humid, your seeds may take longer to dry out. However, even with relatively humid air (>50%), the seeds should dry within 5-7 days.

If you have a dehydrator, you can put the temperature to its lowest setting (usually around 85°F) and dry the seeds for a few hours. This will drastically speed up the process. However, never dehydrate seeds at temperatures above 100°F! Check every few hours until the seeds are fully dry.

How To Know Tomato Seeds Are Dried

To test for a properly dried tomato seed, use a sharp knife to cut through one seed. If it cracks in half rather than squeezing, the seed is adequately dried. This method is useful, because storing undried tomato seeds leads to mold and bad pips!


5. Store Tomato Seeds For 3-5 Years

Once your seeds are fully dried, it is time to choose a storage container. There are a few options, from simple to slightly more complex.

In Envelopes. One of the most highly-recommended methods for storage is in small, loose envelopes. This allows the seeds to continue to dry out, especially if they were not completely dried at the time of storage. This method requires no desiccant packets, just a loose container.

Don’t seal the envelopes in an air-tight container, as this will defeat the purpose. Store them in a cardboard box or a paper bag. Always store your seeds in a cool, dry place (like the refrigerator or a pantry).

In Sealed Containers. I store some of my seeds in a sealed container. However, this requires some added precaution. If you want to store tomato seeds in a sealed ball jar or similar container, first make absolute sure the seeds are fully dried (see above).

Then, add a food-safe desiccant packet to remove moisture from the container once it is sealed. These packets are cheap and useful for many applications, such as storing dehydrated foods.

Dried tomato seeds in baggie
Dried tomato seeds ready for storage.

How Long Do Tomato Seeds Remain Viable?

Seeds are remarkable things. Are they alive, or are they dead? Seeds from 2000 years ago have been successfully germinated and grown into full plants. Seed dormancy really is an incredible process. So how long can tomato seeds be stored?

To put it simply, tomato seeds can easily last 3-5 years when stored properly. Though germination can take longer as seeds age, dried tomato seeds will remain viable for many years.

To elongate the viability, you can store fully-dried seeds in the refrigerator to encourage dormancy early. I store all types of seeds in the refrigerator, especially those that I don’t plan on growing soon.

Note: Avoid storing tomato seeds in the freezer. Although it is possible, there are steps that need to be taken to avoid freezer burn and cracking seeds.


Avoiding Cross Pollination

If you grow many tomato varieties, cross-pollination can easily occur in your garden. This means that a seed saved from a tomato may not grow into the exact same variety from which it was taken.

Cross-pollination can happen in a number of ways. However, the most common is by way of pollinator insects. Bees, butterflies, and other nectar-loving insects will patrol your garden throughout the year, transferring pollen from flower to flower.

If you have two compatible tomato varieties, one’s pollen can fertilize the flower of the other. The resulting fruit will contain hybrid seeds, with a 50/50 split of genetic code.

Some tomato growers don’t want unintentional hybrids, especially if you plan to sell the seeds to customers. Other gardeners (like me) don’t mind an unexpected hybrid in the garden (it can be fun!).

To avoid unwanted cross-breeding, you’ll have to plant different tomato varieties far from one another (300 feet+). This is enough distance to be confident that natural cross pollination will not occur.

Alternatively, use empty tea bags to isolate flowers during blooming. Shake the flowers when they are producing pollen and label the branch once a small tomato forms. The cloth can then be removed to allow the tomato to develop. Save seeds from the isolated tomato only.


Other Questions About Saving Tomato Seeds

There are several other, less common concerns that people have about saving tomato seeds. Here, I’ll answer questions and add to this article as readers ask more. Feel free to comment below with any additional questions you may have!

Can You Grow Tomatoes From Store Bought?

Yes, store bought tomatoes usually contain perfectly viable seeds. Save them for storage using the above methods, or you can plant the seeds immediately after the fermentation process (soaking in water for 2-3 days).

Note: Non-heirloom varieties (hybrids) will likely not grow into the tomatoes you are expecting. F1 hybrid tomatoes will bear seeds with highly variable genetics.

Can You Plant a Whole Tomato?

In theory, planting a whole tomato could result in the seeds germinating. However, it is unlikely to be successful. I recommend removing, soaking and fermenting fresh tomato seeds before trying to plant them.

The reason planting a whole tomato may not work is twofold. Firstly, tomato seeds are surrounded by a protective gel sac that inhibits germination. Soaking for 2-3 days degrades the sac, allowing for better germination rates.

Secondly, in order for a whole tomato to germinate seeds, the seeds need oxygen. The tomato’s skin is an added barrier that may prevent the seeds from sprouting successfully.

If you want to try planting a whole tomato, I would recommend at least slicing the tomato into saucers, first. This will expose the seeds to the oxygen they need in order to initiate germination.

How Deep Should I Plant Tomato Seeds?

Tomato seeds don’t need to be planted too deeply. In fact, plant too deep and the seeds may struggle to germinate.

Put simply, tomato seeds should be planted 1/8 to 1/4″ below the surface of the soil. Cover lightly and spritz with water to ensure the seed is moist and makes good contact with the soil medium.

Why Won’t Tomato Seeds Germinate?

If you are having trouble with germinating your tomato seeds, there are a few possible causes.

For ideal tomato germination rates, use a seedling heat mat to keep seed cells between 75-85°F. Also, use a humidity dome, fanning daily to provide fresh oxygen. Finally, never let the seeds dry out during germination, but don’t overly soak the soil. Even moisture is key.

If you are still having germination issues, your seeds may be old. Older seeds may have entered a dormant state, requiring an extra push to initiate germination. You can try soaking the seeds in warm black tea for 24 hours before planting to help improve rates.

Or, your seeds could simply have low germination. Most seed packets will come labeled with the year they were harvested for and the tested germination rate. If you saved your own seeds, inspect them for proper dryness and any signs of mold before planting. In this case, I recommend planting several seeds per cell to ensure at least one seed sprouts.

Can You Germinate Tomato Seeds in a Paper Towel?

Although the paper towel method is still recommended by some, I don’t endorse it. The method can cause the early seedlings to mold before germinating. Also, the seeds may actually grow into the fibers of the paper towel, becoming difficult to remove.

If you want to get ideal germination rates, use our recommended technique. This basically involves keeping the temperature warm, moisture levels even, and providing plenty of oxygen.

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I hope you found this article useful for saving tomato seeds from your freshly grown tomatoes! Completing the circle of life for your tomatoes is a satisfying accomplishment. Congratulations, and happy growing!

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