fermented seeds

How to Ferment and Collect Tomato Seeds

Introduction: How to Ferment and Collect Tomato Seeds

I have collected over 10000 tomato seeds, for the first time, this year. In order to collect tomato seeds to be used in your garden the following year, you have to first ferment them.

A tomato seed is typically encased in a gel sac. The gel sac prohibits germination. Think about it. The tomato is mostly water and the seeds sit in the tomato at a cozy 80 degrees or more. The tomato itself is a perfect environment for seed germination. The tomato naturally suppresses germination by encasing the seeds. When a tomato rots, it typically is fermenting. The get sac gets dissolved and the seed is now free to germinate. You have to create this process so the tomato seeds will be ready for germination when you need them.

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Step 1: The Jar, the Gel Sac, and Tomato Seeds

You will need a jar with a lid. You can use whatever you would like. The fermenting seeds will smell badly and a tight lid is a good way to manage the smells.

The get sac is the sac that surronds a tomato seed. You can see them easily with the naked eye. They easiest way to collect the seeds is to cut up a tomato and scrape the seeds and the tomato gel and liquid into a large bowl.

You WANT the tomato liquid and gel mixed with your seeds. The seeds need to ferment in the liquid. Try and keep out larger pieces of tomato if you can. The pictures will show you the seeds surrounded in a gel sac and basic other steps.

Step 2: Scrape the Tomato Seeds Into a Bowl and Pour Them Into the Jar

There are no style points for this process. It is a bit messy. Just fill your bowl with the tomato seeds and tomato liquid. When you reached your goal, pour the mix of seeds and liquid into the jar.

The important part of this step is to make sure there is enough liquid in the jar with the tomato seeds to allow the contents room to separate during the fermentation process.

If the jar is about 1/2 full with tomato liquid then add some water to fill the jar to about 3/4 quarters full. If the jar is under 1/2 full then add water to fill it to 1/2 full. You can’t really mess this up so don’t spent too much time stressing about it. My jars are often nearly full to the top because of the tomato liquid.

The pictures are of different points in the fermentation process.

Step 3: Seal the Jar and Let It Ferment for 5-7 Days

Different recipes will tell you different time frames for the fermentation process. I found 5-7 days to be fine. If this is your first time, let them go 7 days. With experience you will be able to eye-ball the seeds and tell when they are ready.

Once sealed in the jar, the fermentation starts within 48 hours. Give the jar a brisk shake each moring. The goal is to remove the gel sac from the seeds. A little agitation helps. On the second day you should notice bubbling and there will be pressure released when you open the lid. So, you do need to open the lid on the second day and smell. It should smell sour and foul. That is GOOD!

You will also notice the liquid and seeds stratify. That is also good. You will see your seeds float to the top. They are most likely your healthy bunch. The other stuff in there will soften and decay and sink. After 7 days you will clean up the seeds.

Step 4: After 7 Days, Pour the Contents Into a Sieve and Rinse

In 7 days you will have tomato seeds that are ready to be cleaned and then dried. You should purchase a fine mesh sieve that won’t let the seeds through. Pour the contents into the sieve and rinse with cold water. You will have to GENTLY rub the seeds along the sieve. The tomato matter left, is decayed, and will easily press through the sieve leaving you hundreds of tomato seeds. Rinse them well with cold water.

Step 5: Dry the Tomato Seeds and Label Them

Tomato seeds will dry and stick strongly to paper towels and napkins. So beware and use coffee filters for the drying process. To set up the seed drying, get a plate and line it with 2 or 3 paper towel sheets. Put the tomato seeds on the coffee filter and spread them out and sit the filter on the paper towels. The water will be wicked away.

The drying process is important. You want to let them dry 7-10 days. Make sure you spread them out nicely on the coffee filter.

And don’t forget to label the paper towels. You will forget what is what if you do more then one variety of seeds.

Step 6: Store Your Tomato Seeds

You can store your tomato seeds in anything really. The best practice is a sealed container, in the dark and in a cool place. It doesn’t have to be the refrigerator. Make sure you label your containers.

Test germination is also something you can do. In brief, just place some tomato seeds in-between damp paper towels, place them in zip lock plastic bag and wait 7 days. They should germinate in 5 to 10 days. I will write an Instructable for the test germination process later.

Please visit my very active gardening blog at the Rusted Vegetable Garden.

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How to Ferment and Collect Tomato Seeds: I have collected over 10000 tomato seeds, for the first time, this year. In order to collect tomato seeds to be used in your garden the following year, you have to first ferment them. A tomato seed is typically encased in a gel sac. The gel sac pr…

Pros and Cons of Fermenting Seeds Before Storage

Most guides to saving seeds from tomatoes, cucumbers, and melons recommend fermenting the seeds before storing them. However, a short perusal of the directions for this procedure is enough to convince anyone that a fermented seed culture is a nasty, smelly mess. So is it really worthwhile? Or is there a better way?

Interestingly, some gardeners don’t ferment their seeds, but simply clean them up with a paper towel. These people suggest that fermenting takes more time and effort than is really necessary. On the other hand, advocates of fermentation insist that the process is essential for ensuring the best results.

So what’s the answer? Let’s find out.

  • Nature’s way. Yes, it’s true. Seeds from certain plants are cleaned by fermentation in nature. Just leave a tomato on the plant to ripen, rot, and fall, and you’ll see it in action. Fermenting seeds mimics the natural process.
  • Enhanced germination. Wet seeds that are embedded in soft fruit crops are often encased in protective gel coatings that keep them from sprouting while still on the plant. Fermentation ensures the removal of the gel, thus guaranteeing good germination rates.
  • Disease prevention. Some plants carry diseases that can be passed on to their seeds and then on to the new crop. During the fermentation process, yeast and beneficial bacteria destroy any diseases that might be lurking on the outside of the seed coat.
  • Bulk benefits. While fermentation may sound complicated to someone with just a few seeds to save, it is actually the easiest and most efficient way to save seeds from a large quantity of tomatoes or other fruits. More seeds means more scrubbing time and effort if you use the paper towel method; on the other hand, the size of a batch of seeds has little effect on fermentation, rinsing, and air-drying time by comparison.
  • Garden etiquette. If you share and trade seeds, you will make them more acceptable to other gardeners by fermenting them. Many gardeners are careful to avoid introducing outside diseases to their gardens, and fermentation will set their minds at ease even if you know that your plants are healthy.
  • Complexity. Fermenting seeds can be difficult even for the experts sometimes. There are many variables which affect the fermentation process, and the project will take close monitoring for best results. Then comes the lengthy washing process and the tricky task of drying the seeds.
  • Odor. Fermenting seeds are notorious for their smell. This is definitely not an indoor project, yet keep in mind that the mixture still has to be kept in a safe place.
  • Drying difficulties. Once the seeds have been fermented and rinsed, they must be dried. For some, this is the tricky part. Drying must take place quickly, or the seeds will absorb moisture and not keep well. On the other hand, they must be dried at cool temperatures, or some of the seeds will be injured or even killed. Seeds stay comparatively dry using the paper towel method.
  • Extra effort. For quite a few gardeners, the paper towel cleaning method works just as well. Why go to needless trouble?


Perhaps the answer to the question of whether fermentation is worthwhile depends on scale. A backyard gardener saving a few seeds for personal use can simply scrub them off with a paper towel and move on without any further hassle. On the other hand, someone growing more seeds, perhaps with plans to trade or sell them to preserve the variety, will want to go the extra mile and ferment them before storage. This person will have to take particular pains to ensure that all of the gel coating is removed from the seeds for both proper storage and good germination, and the paper towel will make slow work of it.

The good news is that gardeners have two equally viable options to choose from when saving seeds. Not everyone has to deal with the messy fermentation process, while those who want to ensure good germination rates and healthy seedlings have a reliable method at hand.

Helpful Resource

Our own online guide to raising vegetables offers tips on saving seeds, including step-by-step directions for fermenting cucumber and tomato seeds.

The answer to the question of whether fermentation is worthwhile depends on scale.