I was ready to move my sad-looking early tomatoes from the garden to the compost pile when I remembered something important. This spring, I used the last seeds of our favorite early tomato, open-pollinated Stupice, so I needed to collect and save a fresh supply of seeds.
My first step was to collect a few ripe fruits free of cracks or bug holes, which can serve as entry points for disease microorganisms. As a precaution against cross-pollination with other varieties, I choose fruits from plants that were grown apart from other tomatoes. I also bypassed double fruits, which are especially prone to crossing with other varieties because of their unusual flower structure. After washing my mother fruits well, I sliced out the middle portions from each one, because that is where the biggest, fattest seeds are found. At this point I decided to use all three of the best ways I know to save tomato seeds: fermentation, simple drying, and planned burial in the garden.
Fermenting Tomato Seeds
Each tomato seed is enclosed in a gelatinous sac. The gel contains chemicals that inhibit germination until the seeds have a chance to glue themselves into soil crevices. This brilliant plan works great in nature, but the gel residue can be a problem for stored seeds because it can provide a safe haven for seed- and soil-borne diseases. The fermentation process is used to clean the seeds before they are dried, but forget about old methods in which tomato seeds are allowed to ferment until a smelly scum forms on the surface of a slurry of tomato gel and water. Several recent studies have shown that tomato seed germination is best when seeds are soaked for only one to two days before they are rinsed and dried, and that fermentation times longer than three days have a negative effect on germination.
This is great news for tomato seed savers, and my own experience bears out that after a mixture of tomato gel and water is allowed to sit at room temperature for 24 hours, the gel sloughs off when the big seeds at the bottom of the container are rinsed well in a strainer. I then dry the seeds on a paper plate for a week or so, or until they feel dry and papery and crack when folded in half with tweezers. If I'm drying more than one variety, I write the name on the plate. When handled this way and given cool, dry storage conditions, tomato seeds usually stay viable for 4 to 6 years, and sometimes longer.
The shelf life of tomato seeds that are dried without first being soaked or fermented may be only one to two years, but that is sufficient time for gardeners who simply want to save seed from one year to the next. You can use the tip of a knife to pick out large tomato seeds from a mass of gel and dry them on a paper plate, or make seed discs or tapes by arranging seeds on small pieces of coffee filter, paper towel, or toilet tissue. I like to cut rounds from coffee filters that fit my seed-starting trays, and put two or three seeds on each one. These "seed discs" can be planted whole, or cut into smaller pieces.
Some gardeners simply squeeze tomato seeds onto a paper towel, spread them out a bit, and allow the towel to dry for a couple of weeks. When dry, the seed-bearing towel can be folded up and tucked into a labeled envelope for storage through winter.
Volunteer tomato seedlings that spring up like weeds are sure evidence that tomato seeds can be saved right in the garden. By late summer I know where I will plant tomatoes next spring, which is always in a spot where tomatoes have not been grown for at least three years. As space in the future tomato row becomes vacant, I use it as seed reservoir by burying cut tomatoes or tomato gel there, covered with two inches (5 cm) of soil and an equal amount of biodegradable mulch. The seeds will not sprout when buried deep, and many survive winter. In spring, I remove the mulch, gently stir the marked place with my hand, and cover it with a cloche to warm up the soil. Tomato seedlings appear like magic.
By Barbara Pleasant.