Tomato Seed Saving and Sowing

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Tomato Seeds Saving and Sowing

Tomatoes are an excellent choice for seed saving because they are self-pollinating and usually grow successfully from seeds.

Tomatoes are in season from late spring to early autumn, but tomato seeds are best planted in late January or early February. This means that they are at their ripest many months before it is time to plant the next crop.

It is important to choose open-pollinated or nonhybrid varieties for tomato seeds saving. The seeds of hybrid varieties will not grow up to resemble their parents and may not taste good.

METHODS OF SEED EXTRACTION

There are basically three methods of seed extraction: (1) juice and seed extraction, (2) acid extraction which is not recommended, and (3) extraction by fermentation, which is the preferred method. Fermentation is the preferred method because it is a natural process that is least harmful to the seed and can destroy bacterial canker and other seed-borne diseases. Fermentation should be a controlled process. Though not difficult to do, it can be done incorrectly, in which case the ferment produces a bad smell and an overgrowth of white fungus which can stain and damage the seed.

Fermentative extraction

The best quality seed is obtained by fermentative extraction. The process basically consists of breaking or mashing up the fruit into pulp, seeds, and juice, and then pouring the mixture (“mash”) into a large container where it ferments for a period lasting usually three days. After fermentation is
complete the seed is separated by washing, and then the seed is dried. Though the process is quite simple there are some important details for performing the process properly.

Part 1: Harvest and Preparation

Tomatoes should be harvested at the "dead-ripe" stage, but they should not be left on the vine so long that there is evidence of decay. They should have developed full color, and the fruit wall will have softened enough to have a slight "give." During very hot weather, I recommend harvesting tomatoes about two days before they are dead ripe so that they can continue to ripen off the vine in the shade. If your growing season is shortened prematurely by frost you can harvest the fruit and allow it to ripen off the plant. Interestingly, seed harvested from immature fruit at the “breaker stage” (when it shows the first blush of color) will often germinate well, but such seeds will not retain their viability as well as seed harvested from fully mature fruit. If you do harvest seed from slightly immature fruit, it should be labeled as such.

Cut a tomato in half, then use a spoon to scoop out the seeds and pulp. Place the seeds and pulp in a bowl and add enough water to cover them. This is done to sort out the viable seeds: the viable seeds will sink to the bottom, but nonviable ones will float. Set the bowl on a windowsill for three to four days. Each day, skim off the floating seeds and pulp and stir the mixture. A very important step, often not mentioned in seed-saving literature, is that the mash should be stirred at least twice, and preferably
three times a day. This helps the ferment to work evenly, helps release the seed from the pulp and its mucilaginous coat. More importantly, stirring prevents the growth of a white scum on top of the mash. This white scum, often accompanied by a bad smell, indicates the overgrowth of a fungus which can injure or discolor seeds. If you see this overgrowth you need to stir the mash more frequently. Keep the viable seeds in the bowl (the ones that have sunk).

The speed of the fermentation process is largely dependent on the temperature. If the temperature ranges between 75 to 80 F (24 to 27 C), fermentation should be complete within 48 to 72 hours. To control bacterial canker, the fermentation should last 96 hours (4 days). This requires a temperature of about 65 F (18 C). This long fermentation can cause injury to the seed, such as premature sprouting. Therefore as a compromise, tomatoes should ideally be fermented at close to 70 F (21 C) as possible. This may be difficult to achieve in practice during the summer unless fermentation occurs in an air-conditioned environment or cool basement. At a minimum keep the fermentation temperature below 80 F (21 C) because a fermentation temperature (temperature of the liquid) in the high 80's can cause a 50% loss of germination in 48 hours. A fermentation temperature

Part 2: Drying and Saving

After three or four days, collect the seeds for drying. Drain the seeds from the bowl and rinse them thoroughly. Spread seeds on wax paper or baking sheet and let them dry for a week. Remove seeds from the wax paper or baking sheet and store in a labeled paper bag or envelope until ready to sow.

Part 3: Sowing

In late January or early February, retrieve the seeds for sowing. Provide potting soil and paper bowls or other kind of container. In each paper bowl, filled with soil, sow four to five seeds 1/4 to 1/2 inch deep. Keep the soil damp but not muddy. Place bowls in a dark area or cover the bowls with damp towels because seeds germinate better in darkness. Check daily for sprouts, and water to keep the soil moist. Once seeds have sprouted, select the healthiest sprout in each bowl and pull out the rest.

When tomatoes reach six inches high, transplant them into pots filled with potting soil, growing bags or in an outdoor garden.

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