Cleaning Tomato Seeds

Posted in Gardening Tips on November 30 2010, by Sonia Uyterhoeven

Sonia Uyterhoeven is Gardener for Public Education.

We have spent the past few weeks talking about cleaning and storing your seeds. I mentioned a few blog entries ago that a simple way to clean and store tomato seeds is to squeeze out the contents of the tomato and soak it in water – washing away any coating that surrounds the seed. You then dry the seeds on a paper towel and store.

Aficionados have a more elaborate method of cleaning tomato seeds that involves fermentation. Tomato seeds are surrounded by a jelly-like coat that contains a germination inhibiting substance. The coat prevents the seeds from germinating too early so that tender seedlings do not emerge in the fall or winter.

Fermentation also protects the seeds against bacterial canker and is a good way of ensuring that your seeds are disease free. Fermentation is not the only way to control seed-borne diseases. Washing seeds in plain water, in salt water, in hot water (around 122°F – boiling water is 212°F – so this is just hot water) for 15 minutes are all methods for controlling seed-borne diseases.

The process for fermenting tomato seeds is simple. Scoop out the seeds and all the pulp and juice into a glass jar. Cover the seeds with water and set the seeds aside storing at room temperature. Check daily and stir the mixture. After 3-4 four days the viable seeds will have sunk to the bottom and the pulp and any poor quality seeds will have floated to the top (they are lighter). Pour off the gunk from the top; strain out the seeds and rinse in a sieve.

Dry on a paper towel and store in a Ziploc bag or plastic container in a cool, dark place. The seeds will stay viable for up to 4 years. Remember not to store your F1 hybrids as they will not come true to seed. Your heirlooms are ideal for storing. Most tomatoes are self-pollinating but you do get cross-pollination from time to time.

If you want to make sure that your tomatoes don’t cross-pollinate you can create a barrier by covering them with a pollination cage – use remay or a fine mesh screen so that bees will not be able to your plant – or you can space different varieties at a good distance from each other. There is a difference in opinion on spacing – some say 10 feet is sufficient – others 25 feet and some say for truly pure seeds you need up to 100 feet. For the homeowner, crossing of heirloom seeds should not be a major issue – leave that concern for the grower.