How to Ferment and Collect Tomato Seeds

Tomato Vegetable Gardening and Seed Collecting



Tomato seeds need to be fermented to remove a gel sac that surrounds them. Fermenting the seeds prepares them for germination. This Knol article teaches you everything you need to know about fermenting and collecting tomato seeds.

How to Ferment and Collect Tomato Seeds

By Gary Pilarchik LCSW-C
Visit my very active tomato and vegetable garden blog for more information: The Rusted Vegetable Garden
I have collected over 10000 tomato seeds, for the first time, this year. In order to collect tomato seeds, 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 in order to collect tomato seeds that will be ready for germination when you need them.

Step One: Identify the seeds & notice the gel sacs around the tomato seeds.

Tomato Seeds in Gel Sacs: Gary Pilarchik
Tomato Seeds and Gel Sacs: Gary Pilarchik
The seeds of all tomatoes will by covered in the gel in some form. Fermenting the tomato seeds in a jar will dissolve the matter that surrounds an inhibits germination. If you don’t do this, your seeds will still probably germinate but instead of taking 5-7 days to sprout it can take weeks or longer. 

Step Two: Collect the tomato seeds in a bowl.

Remove the Tomato Seeds into a Bowl: Gary Pilarchik
Collect the Tomato Seeds: Gary Pilarchik
It is pretty straight forward, scrape out all the seeds you can and try and keep excess tomato chunks out of the mix. It is okay if you get some random bits and pieces in the mix of seeds and liquid. The fermentation process will soften all tomato matter.
A Bowl Full of Tomato Seeds Ready for Fermentation: Gary Pilarchik

Step Three: Place the tomato seeds and liquid into a jar with a lid.

Fresh Tomato Seeds in a Jar: Gary Pilarchik

Black Cherry Tomato Seeds Ready for Fermentation: Gary Pilarchik

You can buy mason jars or use pickle and olive jars. When the mixture ferments, the yeast process produces gases. You should open the jar once a day to let the gas out. Fermentation is a process that is started by natural yeast. 
The jars should have enough liquid to fill up about half the jar. You can add about 4 ounces of water to the mix if you need to add volume. I have found the process works with or without the addition of water. Notice how the tomato seeds in the pictures have a lot of volume to float around in. You want enough liquid in there so the seeds have room to settle.

Step Four: Let the tomato seeds ferment 5 to 7 days.

Once you put them in the jar, let them sit out of direct sunlight for 5 to 7 days. The key to success is that fermentation happens. You will notice it happens when gas builds up in the jar and the mixture stinks.  Don’t worry if you see mold and fungus. That is nature and that is success. You really don’t want go past 7 days. There is no need and the seeds could potentially germinate in the liquid.
  • Ferment 5-7 days
  • Keep jars out of direct sunlight
  • Open the jars 1x daily to release gas
  • Swirl jar contents gently 1x daily
  • If it stinks it is working


Tomato Seed Fermentation: Gary Pilarchik

I put them by the window for the picture. Keep the jars of fermenting tomato seeds out of direct sun light. You will notice your mixtures settle. The seeds that fall to the bottom are healthy and free of the gel sac. This settling occurs around the 2nd day of fermentation. You should swirl the contents 1x daily.  Different tomato varieties settle differenlty.

Swirling them helps the seeds agitate away the gel sac. Fermentation would probably work just fine but you just have to do something while the jars sit there.

Step Five: Fully fermented tomato seeds need to be rinsed clean.

6 Day Old Fermented Tomato Seeds: Gary Pilarchik
What I learned is that different varieties do different things in the jars. Seeds sizes vary as do the the gel sacs. Some tomato seeds drop to the bottom the first day. Some stay caught in the matter but are gel free after a few days. Some do both. Swirling them helps with separation. As long as you know they are fermenting and wait 5-7 days, nature will take care of business. 
Rinse the Fermented Tomato Seeds in as Sieve: Gary Pilarchik
Fermented Tomato Seeds: Gary Pilarchik
Rinse the Tomato Seeds: Gary Pilarchik
The contents need to go into a sieve. This is the easiest and quickest way to clean your seeds. Rinse the fermented tomato seeds in cold water. Gently move them around and let the tomato matter rinse away. You will notice the gel sac are completely gone.

Step Six: Place the cleaned tomato seeds on coffee filters to dry.

Dried Fermented Tomato Seeds: Gary Pilarchik
Place the cleaned tomato seeds onto a coffee filter. Tomato seeds will painfully stick to paper towels. I learned the hard way. The best thing to do is place a few sheets of paper towels on a plate to absorb the water. Put the seeds on a coffee filter as in the picture. Make sure you label the seeds. You will forget.
Tomato seeds should dry for 7 days. They need to be dry enough so when you place them in a storage container they won’t mold, rot, or germinate. They should be dry to the touch, look like tomato seeds from a packet and be slight hard to the bite or the finger nail. After the paper towels are mostly dry, run your fingers through the seeds daily to move them around and help with uniform drying.
Once dried, store them in a dark place in some sort of air tight container. I find there are plenty of small containers for storage at your local hobby shops. DON’T forget to label them!


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