Tuesday, March 13, 2012

Processing Tomato Seeds

With tomato seed offered by catalogues becoming so expensive it is no wonder that many gardeners are choosing to save seed for themselves. While my early attempts at saving tomato seeds left me with pretty unworkable cakes of seedy pulp stuff I now save tomato seeds very easily through the process of fermenting. All that is required is a few simple tools and a little bit of patience.

First things first – find your favorite open-pollinated (non-hybrid) or Heirloom tomato plant and pick yourself some very ripe or over-ripe tomatoes. Tomato seed is often at its best when the fruit is over-ripe though good seed can often be extracted from barely ripe fruit.

Selecting Hahms Gelbe Tomatoes for Seed Processing
Next, you cut the tomato and squeeze out the pulp containing the seeds. When you are done squeezing out the tomatoes, you can add ½ the amount of water to seedy pulp, if desired. This may make seed processing easier for later. You can eat the outside layer of processed tomatoes, if you want. My kids sometimes stand next to where I am processing seeds and eat the outside layer when I am done squeezing out the seeds. Then put a lid on the container, label the container (if you are doing more then one type of seed) and wait.

Squeezing Tomatoes for Seed Processing
What are you waiting for? You are waiting 1-5 days until the container produces a rotting odor and develops a bit of fuzz or a floating mat of mold. Yum! You may now be wondering why anyone would even do this. The reason why fermentation is so helpful in processing tomato seed is that fermentation breaks down the bubbles of slimy pulp covering the tomato seeds (which helps with seed storage and use) and kills pathogens that could lead to disease in the next generation of tomato plants.

A layer of mold has now formed on top of pulp mixture
Next, remove the floating mat of mold and pour the seedy slimy mixture into some form of sieve or screen, saving the slimy pulp for now. You might need the pulpy mixture later if the mixture didn’t ferment completely. A relative gave me my screen thingy. She said she probably obtained it from a dollar store or Walgreens.

Rinsing out Tomato Seeds
Wash out the seeds very well. If you hold a wet seed in your hand you should feel no pulp, but instead notice a very small layer of fuzz around the seed. This means you can now throw away that nasty slimy mixture. If the seeds still have a slimy coat that cannot be removed you will need to put the pulpy mixture and seeds back into the fermenting container and wait to rinse again later. If the seeds do not ferment long enough then they keep their slimy coats while if they ferment too long they will turn dark and may not sprout when planted.

Rinsed out Tomato Seeds in my Sieve thingy
The next step should be straightforward. Put the seeds on a paper plate or something else that you can label and put in a dry undisturbed place. I have to say undisturbed because I have small children – so my undisturbed place happens to be above our cupboards. After a day of drying, I stir my seeds to see if they are dry all the way. Then write the name of the variety and the year on a bag with permanent marker, along with anything else I might want to know about the seeds and put the seeds into storage.

Hahms Gelbe seeds ready to dry

Some finished seed - Notice the fine hairs on the seeds

I hope that this little tutorial is helpful. In relation to seed saving, tomato plants are not very susceptible to inbreeding depression, meaning that the seed from just one healthy plant can produce a large number of high quality seeds to grow future generations of tomato plants. The ease of saving tomato seed is probably why so many tomato seed companies have sprouted up recently (no pun intended).


  1. Don't forget that if you want the seeds to grow true to type, the bloom should be isolated if there are any other tomato types in the vicinity!

    My seed saving attempts give me blobs of seeds gobs too. Primarily because I usually forget about them and don't rinse them before the fluid all evaporates.

    1. Thanks for the advice! I have very few, if any bees in my area right now and I pollinate all of my tomato plants by hand, which isolates them from cross-pollination. Come to think of it, I have never seen a regular bee pollinate my tomato plants, though I have occassionally seen some wild bees doing so - in the middle of the summer.

      I used to think that processing tomato seeds via fermentation was too much work - but the process cleans the seeds so well that the work is well worth the reward!

  2. This is really an informative article. Thanks for sharing. I hope to collect some seeds this summer. I will definitely try. By the way, do you know why I should choose open-pollinated or non-hybrid to save seeds? Is it because the hybrid seeds will not produce seedlings?

    1. You asked a good question.
      A hybrid is a child plant of two varieties that can have drastically different characteristics. If you would like to save seed from a hybrid plant you need to save a lot of the seed from that plant, then you may need to grow a lot of plants until you find the tomato plant with the same characteristics as the hybrid that you grew. You may get incredibly lucky the very first time and grow a plant that is just like the hybrid. Though for the most part, your chances could be as good as 1 in 8 or as bad as 1 in over 300, meaning that you may have to grow a lot of plants to find the one that has the same characteristics as the hybrid. Once you do this, you have to select for the characteristics that you are looking for until the 6th generation of the hybrid or the F7 before the tomato plant will be a stable open-pollinated variety. Until that time there will be a lot of plants that your seed will produce that will not be anything like the initial hybrid. I really recommend you try to read a copy of Carol Deppe's "Breed Your Own Vegetable Varieties" if you are interested in de-hybridizing hybrids. If this is not something you want to do the work to do, I suggest you stick with open-pollinated or heirloom varieties, which will reproduce plants that are very similar to the parent plant.

  3. Hi Jay, I had the same question as the previous commenter and so am glad to have the extra benefit of your answer. This was a very interesting post to read. I had no idea how to collect tomato seeds and now I do!

    1. Dear Jennifer,
      Thank you so much for your comment. I'm glad I could help. I'm still learning a lot too!

  4. Very interesting! I had no idea! I have yet to save veggie seeds (indeed I have yet to get a really productive veggie garden going), but this is definitely something to remember for the future. There's just something so great about using generations of seeds that you keeping saving throughout the years. And it gets you basically free plants!

  5. Jay,

    Thanks for the reply. I was getting confused why people advise against hybrids. I thought they would not be producing any seedlings. Now, I know better :-).


    1. Thank you for your reply!

      I have one tomato hybrid I would love to de-hybridize - Celebrity. Alas, selecting for disease resistance and fruit type is incredibly difficult! I believe the fruit of the disease resistant parent is quite different from the fruit type of the F1 we know of as Celebrity.

  6. Thanks for this article. Great blog. I'm going to read your archive today!!
    I don't know if this is important to you all, but Celebrity tomato is a Monsanto seed. I personally won't use any of their seed. I grew a celebrity tomato plant last year before I knew about Monsanto. It really is an awesome tomato, I'll miss it.

    1. Thank you for your comment!

      My understanding is that Monsanto did not develop Celebrity but rather Celebrity is owned by a company that Monsanto bought out. Monsanto does make money off of each Celebrity seed sold - though I am hopeful that in the future someone will select a stable and disease-resistant open-pollinated descendent of Celebrity with all of Celebrity's positive traits. Celebrity is protected by the fact that the parents of the hybrid are unknown. However, as disease resistance is controlled by many genes, the F2 (second filial generation from making a cross) seeds from a Celebrity tomato may have to be grown in a big field of hundreds of plants to select for all the virtues Celebrity has. Additionally, such a variety would have to be sold under another name. I do occasionally buy Celebrity plants only as a standard to determine what qualities my open-pollinated varieties have to measure up to in order to remain in my garden.

    2. If you like Celebrity, I would highly recommend Siletz (sold by Territorial Seed Company). It has many of the qualities of Celebrity with a much better taste. Siletz seed is a bit pricy but it is open-pollinated and very worth the price! I wrote about it in one of my posts under "Tomatoes". If you choose to grow Siletz and want to save seed, make sure to get out there with a paintbrush when the blossoms are young to pollinate them. Otherwise you may end up with large seedless tomatoes.

  7. Thank you jay
    the tutorial was easy to follow... we so happy we got out first batch of seed... all your post are helpful for a beginner like us.thank you once again

    1. Dear Aish M,

      Thank you so much for the compliment. It has been hard living without a garden since moving to California. Hopefully, I can start growing one again soon!

      Happy Gardening!


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