Step by Step: Saving your own tomato seeds

Step by Step: Saving your own tomato seeds

As the air turns crisp and cool and everything gets covered in this golden tone we know fall is coming. The garden prepares for a long rest and we collect the last little treasures of our harvest.

And most importantly we collect the seeds for our next garden year.

In this blogpost I want to share with you how you can save your own tomato seeds, since the process is a little different compared to most plants. The reason for that is the germ – inhibiting coating that tomato seeds and also cucumber seeds have which protects them from germinating before they are supposed to.  When you rub the seeds between your fingers you can feel the slippery coating. You do not need to get rid of the coating (they actually last longer with the layer on them), but it makes the germination more difficult and it is a place for diseases to grow, so if you are planning on using your seeds the following year it is a good idea to remove it and I will show you how.

The method we use for this process is FERMENTATION.

In order to ferment your tomato seeds you need:


  • jars
  • water
  • knife and spoon
  • sugar
  • sieve
  • coffee filter

and of course your tomatoes! Make sure you only pick ripe and healthy tomatoes from reproducible varieties in order to get high quality seeds.

Step 1

Clean your jars (one jar per variety) and place them in front of your working area. Then cut the tomatoes you choose in half and with a spoon scrap out the pulp and the seeds into your jar.

Step 2

Now cover the pulp + seeds with water and put them in a place where it is relatively warm, about 23 – 30 degrees works best for fermentation. You can add a tiny bit of sugar when you feel like you do not have a whole lot of pulp and therefore not a lot of fruit sugar. The fermentation should now happen on it´s own and in about 2 days we can collect our seeds.

In the picture you can see that I did not have any lids on top of my jars and that was not a great idea. Within a couple of hours I had a bunch of dead fruit flies in my water so I recommend covering the jars – either with a net or by laying the lid on top. Just don´t put the lid on properly because you can have the issue that pressure builds up inside because of the fermentation.

Step 3

After one day I already had a thin white coating and the jars smelled like kombucha – so the fermentation was definately happening. If you want to check whether coating is already gone or not you can use a clean spoon, take out a seed and rub it between your fingers. If the seeds do not feel slippery anymore and instead feel abrasive it is time for the next step. If they still feel slippery they still need a little bit longer.  For my seeds it took about 2, 5 until they were ready.

Step 4

Fill your jars up with water. The empty seeds and the pulp should now swim on top and the good seeds should sit at the bottom.

Dump the stuff from the top in the sink so you only have the good seeds at the bottom left. In my case I still had a little bit of pulp at the bottom but that is no problem since we still have to rinse the seeds in the sieve.

Fill the jars with water again and pour everything in a sieve. Now we have to give the seeds a good rinse! 

You don´t want any bits of pulp left on your seeds so make sure you clean them well.

Step 5

After cleaning they just need to dry before we can store them away for the next year. I used coffee filters to dry the seeds on but I heard that baking sheets work too. The coffee filters work great since they absorb a lot of water. This step is very important because the seeds need to be completely dry before being stored in order to prevent mold. I had my seeds out in a sunny place for a couple of days and then put them in little brown paper bags. Don´t forget to put labels on the bags if you have different varieties ;).

Now we just need to wait for spring until we can plant again!



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