As this is my first year saving seeds, I had to look up the process. As usual, there are different opinions on best techniques. The most common way is fermentation. Those that use this technique do so because they want to remove the gelatinous material that coats the seeds. This goo prohibits seeds from germinating. Mr. Brown Thumb has a great post on how to save seed by fermenting, with excellent photo instructions. Tatian’s TOMATObase also provides some clear and detailed instructions.
Fermentation is kind of icky, in a fascinating way. I did not let it get to the same state as Mr. Brown Thumb, with the mould on top. What I did was take seeds and soaked them in a small tea cup, using tap water. I covered it with Kleenex and an elastic band and left it on my counter. At this point, some of the seeds sunk, and some floated. Over the next couple of days, the goo loosened, and I would rinse several times and let it soak in clean water. By the third or fourth day, I would gently rub the seeds, rinse clean, and lay the seeds out to dry on a clean plate. Note that there might still be some remnants of gel – hopefully this won’t affecting germination next year. There was a small batch that I had left in water inadvertently for close to 1 week. When I checked on it, they had all started germinating! Those are the ones that I planted in soil, and they are growing and look healthy.
With the latest batch, I only let it sit in water for 3 days. I let it dry for 2-3 days, and have stored them in a paper envelop.
The gel coating inhibits germination, which makes sense because you wouldn’t want the seeds to begin germinating inside the tomato. The reason you need to remove this coating is because you want to store seeds dry, to eliminate any chance of disease. I found this post, that states that fermenting longer than 3 days have a negative effect on germination (no sources quoted). Now I am thinking that maybe I should have left them on the plate to dry for longer. I will have to check on them, but I still have more tomatoes on the vine that I can scoop seeds from.
One other tip I received from a farmer was to let a tomato rot on the vine and take the seeds from it, because all of the energy has now been stored in the seeds, and the longer you leave the tomato on the vine, the more seeds you will get.