Once I became hooked on growing my own tomatoes and other food, I wanted to start saving the seeds from what I grew so I could use them the following year.
The principle is simple: make sure the plant you want to save seeds from doesn't become cross-pollinated by another plant of a different variety.
So if I want to save seeds from my San Marzano tomatoes, I want to be sure the blossoms aren't pollinated by my Striped Roman plants.
An easy way to do this with self-pollinating plants like tomatoes is to use blossom bags. You can make them yourself out of fine mesh organza if you have the sewing gene, or you can buy them online. I like the ones that Seed Savers Exchange offers, they're not too expensive and well made. They work well for things like tomatoes, peppers, eggplant, and even beans.
|Blossom Bags from|
Seed Savers Exchange
Once the fruit is formed you can gently remove the bag, and mark the fruit for later collection and saving. (I use a twist tie or piece of a pipe cleaner.) Let it ripen, and once it has, harvest it.
Certain seeds, especially tomatoes and cucumbers, should be fermented for a few days to remove germination inhibitors and soften the gelatin coating that covers them. Doing so is simple, and you can use a mason or other jar. Others, like pumpkins and squash, can just be cleaned and dried.
For wet vegetables like tomatoes, rinse the tomato well in water to remove any dirt or fungus clinging to the skin. Then cut it open, and scrape the gelatinous material that the seeds are in out into a jar. If the tomato is very dry (like a paste tomato) you can add some water, but you don't always need to if the fruit is wet.
I cover the jar with a piece of paper towel secured by a rubber band, and put the date on the jar. You want to let the seeds ferment for several days at about 70 degrees (the top of a fridge is a good place for this.)
Once or twice a day give the jar a swirl, during which you'll notice some of the seeds sink to the bottom. Those will be your most viable seeds, and the ones you want to save.
After three days, put another one or two inches of lukewarm water into the jar, and swirl it around again, then let the seeds settle for a minute or so. Then gently pour the top later of gunk out of the jar, which will take with it some of the seeds that didn't sink. Rinse the remaining seeds several more times using a very fine mesh strainer, making sure there is no gelatinous material clinging to them.
Next comes a step you can skip if you're just saving the seeds for yourself, but you really should do if you're going to sell or give the seeds to anyone else. You want to ensure there are no fungi or molds on the seeds before you dry them, so a quick rinse in a 10% bleach solution is needed.
Be sure to use just a plain old 5.25% bleach, not concentrated or with any fragrance. Just the cheap stuff. Make a ten percent solution by adding 4 1/2 teaspoons of beach to one cup of pure water, or 1 1/2 cups of bleach to one gallon of pure water if you're doing a lot of batches at once. Note, you must discard each batch after use (don't reuse it on another batch), and it will only keep for about 12 hours. So smaller batches works better I find.
Now sources differ on how long to leave the seeds in a bleach solution, some say you must do so for 30 minutes, some as little as a minute. I leave mine in the solution for about five minutes, swirling them around about once a minute to be sure all the seeds make contact with the solution.
Note that some people use a stronger solution (1 part bleach to four parts water), they are the ones who leave the seeds in for the shorter amount of time.
|Drying seeds on a paper plate|
Once you've finished the bleach soak, rinse the seeds very thoroughly to make sure no traces of the bleach remain. Then dump them out onto a coffee filter or paper plate to dry, labeling it with the type of seed and the date processed. Be sure to spread them out so they dry evenly, and swirl them around on the second day and each day afterwards (they may stick to the filter or plate, if so gently pry them loose and stir.) I leave mine on top of a bookcase for about a week. After that, you're done!
You will want to put them into a small paper envelope for storage, and then into an airtight container like a mason jar (I don't like putting the seeds in small ziplocs for long term storage, although I do use those to ship seeds to friends.) Some people store their seeds in the fridge, I don't have room in mine for seeds so I keep them in my cool basement.
And there you are! Seeds kept from your own plants which you can use to grow more of them.