Wednesday, 14 September 2016

How to save tomato seeds

Saving seeds is normally just a case of drying them when they are ripe, but some seeds benefit from a bit of extra care - like tomatoes. The seeds of a tomato are encased in a sort of jelly, which has anti-germination properties to stop the seeds germinating too early, inside the fruit. If this "jelly" is not removed, the germination rate of the seeds you save may be low. I'm going to describe how to do this. Obviously the method I use is only suitable for small-scale production; a commercial grower probably does things a bit differently.

The first thing to do is choose a good tomato - one which is a good specimen, and fully ripe if possible. It makes sense to choose your best fruits as your "breeding stock".



Cut the tomato in half (horizontally is best, because this way the seeds are more readily accessible), and scrape out the seeds and their surrounding pulp (aka jelly).



Transfer them to a suitable container. A glass jam-jar is ideal, because you will be able to see into it to monitor progress.



Now add cold water so that the seeds are covered to a depth of an inch or so. Swoosh it around a bit, which will help to to separate the seeds from the pulp. Cover the jar with a piece of kitchen paper or something similar (it needs to be porous), and hold it in place with a rubber band. This will stop flies getting into the jar, and will reduce the inevitable odour.



Set the jar in a warm (but not hot) place, and leave the pulp to ferment. It will grow a mould as it ferments. This will take somewhere between 2 and 4 days, according to the amount of warmth. Eventually the mould should cover the whole of the surface, like this:



What should happen is that the pulp will rise to the top (and ferment), whilst the heavier seeds drop to the bottom. The fermentation process will remove the anti-germination properties of the pulp / jelly.

Once fermentation is complete, the next step is to remove the mould, which will normally be possible to peel off in once piece, using a teaspoon or similar implement:


Once you have removed the mould, tip the seeds and remaining liquid into a fine-mesh sieve.


Hold the sieve under a running (cold water) tap and try to wash away all the pulp. It will be pretty soft by this stage and most of it will pass through the sieve with a little gentle persuasion.



Then tip the seeds out of the sieve onto a small dish. Do not put them onto kitchen paper because they will stick to it as they dry. Try to remove any pieces of flesh or pulp that did not get washed through the sieve. Place the dish of seeds somewhere warm and dry - for instance the airing-cupboard - and leave them to dry for several days. Don't be tempted to hasten the process by adding heat, because this would damage your seeds.

As the seeds dry, it is a good idea to try to separate them (perhaps use a wooden cocktail stick) rather than allowing them to form clumps. I have found that a week in the airing-cupboard is about right. The end result will look something like this:


If you are saving more than one variety of seed, don't forget to label them!


When you are satisfied that the seeds are completely dry, put them into an envelope (labelled!), and store them in a cool dark place until sowing-time.

Job done!

11 comments:

  1. We just pull the seeds out with fingers onto a cloth and wait till next year. It has worked for this year. Also I have a few self seeded tomatoes where the rotten tomatoes just fell off and got dug over. Never worked out why people go to these lengths but you mention the "anti-germination properties of the pulp / jelly." - I never knew that was the reason.

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  2. Interesringly we get self sown tomatoes in pots in the greenhouse where tomatoes have fallrn from a plant and rotted unnoticed.

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  3. I've saved tomato seed for the first time this year - did more or less the same way as you suggest except that I didn't cover them but did place the container in the garage. I actually didn't think about the fly issue but it didn't seem to be too much of a problem. We'll see if I did a good job come next year when I sow them!

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  4. Great info Mark! I just finished drying some today. I use a paper coffee filter, and they don't stick to that like they do a paper napkin or towel.

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  5. I wasn't aware of the fermentation process. This is interesting. Every year I have a lot of tomato re-seeders so I haven't really bothered with the seeds. I'll give this a try. Advice from someone who grows such a variety of vegetables in a small space, is valuable. I just checked out the link to your interview. Enjoyed reading it.

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  6. I'll have to give this a go. I never knew this was possible!

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  7. I'm not sure the heat would really hurt. I've grown tomatoes with seeds from commercially canned tomatoes!

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    1. That's amazing. I would have thought cooking them would have killed the seeds.

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  8. What germination rate do you find you normally have? Do the plants always come true from their parents?

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    1. This is my first time saving my own tomato seeds, so I can't answer those questions. Germination rates in commercial tomato seeds are always pretty high.

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  9. I saw this comment on an article on Facebook about growing tomatoes directly from a fruit. If you ignore strange wording, the message is clear: "...without fermenting the seeds properly, the mother tissue residue will carry pathogens from previous seasons increasing the probability and severity of diseases like septoria, early blight, and verticillium. The reasons we ferment tomato seeds are not trivial and not isolated to our own gardens as neighbors will surely be impacted by spreading pathogens. The worst strains of late blight to evolve taste for tomatoes arose in 2009 due to improper propagation of Bonnie Plants brand tomato plants sold at Home Depot. Today the new races of conjugated late blight are still perennializing in the north and bloom every year. it rendered the PH2 recessive expression for resistance nearly pointless since, setting tomato breeders back decades if not a century. it is our responsibility to care for the seeds properly and not to grow tomatoes without proper fermentation.

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