Saving Tomato Seeds

Striped German - Heirloom tomato

One of the missions of the Sharing Gardens is to educate people about the importance of seed-saving and to offer techniques to demystify this process. Today's blog covers the practical steps necessary for saving one of the home-gardener's favorite fruits: the tomato! If you're new to seed-saving tomatoes are good to start with because of their relative simplicity.

In order to save seeds that will "grow true" and produce fruit similar to the one you saved seeds from, you must start with an "heirloom" or "open-pollinated" (OP) variety (not hybrid). Hybrid seeds are artificially created by seed companies to produce plants with unique qualities (early ripening, bug resistance etc). The problem is that they don't "breed true". If you save seed from hybrids, next year's plants may or may not be what you want. If you wish to save seeds, choose seeds or starts that say "open pollinated", OP, heirloom or non-hybrid.

 

"Heirloom" tomatoes come in all types: here are large paste-tomatoes called "Long Toms"

 

OK, so lets say you have grown some beautiful heirloom tomatoes and you're ready to save seeds. If you have more than one plant to pick from, choose the plant that is healthiest, most robust, earliest to ripen and with the largest and/or best-tasting fruit. Then, pick several fruits that are the best examples of these same qualities. If you've grown out several plants of the same variety, save seeds from multiple plants to keep  genetic diversity.

 

If there are other people who harvest from your garden, put a twist-tie, or in some other way mark the fruit so no one picks it prematurely. We often use onion or citrus bags (plastic, stretchy netting - Left) so we can actually cover the fruit, making it clear that it's not to be picked. Let the fruit come to fullest maturity possible. It's OK even if it starts to rot a little.

Black Krim (below) and Striped German

Here are two heirloom tomato varieties we saved for seed this year (right). We saved them as beautiful examples of color, juiciness and size. That's a Black Krim on the bottom and a Striped German on the top.

In saving seed, you wish to mimic nature's process. Have you ever noticed what happens to the tomatoes left in the garden after the first frost? They turn to a slimy mush, with the fruit eventually dissolving away from the seed. In the following year, robust little volunteers emerge from where the tomato rotted. The way we mimic this process: 

Remove the stem from your chosen tomato and put it in the blender with enough water to fill a quart jar. (We have well-water which has no chlorine and I'm not sure if chlorine would be a problem so, for best results, use filtered water, without chlorine.)

Whiz it in the blender, at a low speed, just long enough to separate seeds from fruit. Don't worry about the seeds. They have a protective gel that keeps the blades from harming them. Pour them into a wide-mouth glass jar. Be sure to swirl the blender as you pour the last liquid out so no seeds are left in the bottom. 

If you're processing more than one tomato variety in a row, rinse the blender well so you don't mix seed varieties.  

Label the jar so you remember the variety of seeds you're saving.

The next step is to leave them to "rot". To minimize fruit-flies secure a piece of cheese cloth over the opening with a rubber-band or canning-jar ring. Leave them in the open jar for 4-7 days. When it's warm outside, the process will go faster. Stir them once or twice a day with a chopstick to help separate the seeds from the pulp. The pulp and non-viable seeds will form a layer at the top. The healthy seeds will sink to the bottom. Look for a nice scum to form on the top. Mold is OK. The picture below, on the left is of two varieties of tomato seeds in process. The ones on the right were just blended so no layers have formed. The ones on the left have been sitting a few days. The other picture shows the quality of the scum that has formed on the tomatoes once they are ready for the next step. Notice the bubbles which indicate a mild fermentation process.













The last step is to dry the seeds. Spoon out the scum and pour off most of the water. The viable seeds will have sunk to the bottom but be careful not to pour them out with the pulp/water. Add more (filtered/well) water, allow to settle and continue to pour off excess flesh. Repeat this process till you've removed the majority of the flesh and are left with just seeds and water (or as close to that as possible). 

 

Then pour the seeds through a fine-mesh strainer and rinse them in the strainer. Let them drip-dry and then tap them onto a piece of tin-foil, a jar-lid or other non-porous surface. We find that the lid to a plastic tub (like a yogurt container) works best as it's flexible and we can "pop" off the seeds after they've dried. Seeds will stick to paper towel or napkins. 

 

Transfer your label to the drying seeds and leave them to dry for a week or so. Place them on a table or shelf out of direct sunlight and safe from animals (we had a whole batch of seeds eaten by a mouse when we left them on a low shelf they could access). Be sure they are thoroughly dry before storage so they don't mold in the bag, envelope or jar.

Each seed-saver has his or her preference for containers to store seeds in. We use clean, small plastic bags or recycled plastic pill-bottles or other small jars. The most important thing is to keep your whole seed collection in a dry, dark environment with moderate temperatures, in air-tight containers. Avoid freezing or excessive heat. Stored well, tomato seeds can remain viable for many years.

Tomato seeds drying.