How to Save Tomato Seeds: Step-by-Step Instructions

1. Harvest Tomatoes

   Carefully pluck ripe tomatoes from healthy parent plants. In order to selectively breed the best tomatoes possible, only choose tomatoes that are in good condition.

   Avoid tomatoes that are misshapen or come from plants with pest damage, as those traits may be hereditary and the seeds you save from them may experience similar setbacks when they grow.

2. Remove Seeds, Juice, and Pulp

   Cut each tomato in half and squeeze the seeds, juice, and pulp of your tomatoes into a container (a glass canning jar works).

   Make sure the seeds are completely covered with pulp and juice so they can properly ferment. Avoid adding water to the mixture if possible, as dilution can slow the fermentation process you’ll rely on to save the seeds.

3. Start Fermentation

   A jelly-like sac surrounding each tomato seed prevents germination until the seeds are exposed to soil, which is great, except that the sac can harbor disease. Experienced seed-savers use fermentation to rid the seeds of their sacs before drying and storing them for future use.

   Once the seeds, pulp, and juices are all squeezed out into a bowl, label the bowl “tomato seed ferment” with the date and set it aside to let the fermentation begin. You can cover the container with a lid or cheesecloth to keep fruit flies away and to help contain the ferment’s unpleasant smell.

4. Check on Fermentation

   Leave your seeds to ferment for 1 or 2 days and check on the process once or twice daily. Fermentation times longer than three days can negatively impact the seed’s viability. After fermentation, the mixture of seeds, pulp, and juice should have a thin layer of mold over it. This may look and smell gross, but it’s a sign that the fermentation process is working.

   If there is no layer of mold after 2 days of fermentation, don't worry. It may not have had time to develop yet, but that doesn't mean the ferment didn't work. Check to see if the seeds have all settled at the bottom of your container with layers of watery juice and then pulp on top. If these layers are present, your ferment is complete.

5. Pour Out Liquid

   Pour out excess liquid from your tomato slurry, including all pulp, juice, and mold that may have formed in your container.

   You’ll strain the mixture again in the next step, so there’s no need to completely separate the seeds yet. Just pour off what you can without sacrificing seeds to make the straining process easier. Dispose of unneeded pulp, juices, and mold in your compost bin.

6. Strain Mixture

   Now pour the seed mixture through a cheesecloth or a fine-mesh sieve into a separate large bowl or bucket to completely separate all seeds from the liquid. You can spray any stubborn pulp with your water faucet.

   Rinse the seeds thoroughly under running water to get rid of all of the pulp and juices possible. Again, you can dispose of the unneeded pulp in your compost bin.

7. Dry Seeds

   Drying tomato seeds completely after fermentation will allow them to stay viable for up to 10 years. To do this, you can flip the strainer over and empty the clean seeds onto paper plates.

   Spread the seeds out so they have room to dry. Set them aside until they are completely dry (about a week) in a relatively cool, well-ventilated area. To stop the seeds from clumping together, shake the plate daily and rub away any clumps that do form.

   If you’re drying multiple tomato seed varieties, make sure you label them and avoid mixing seeds to prevent cross-contamination. That way, you’ll know exactly what you’re planting when it’s time to garden.

8. Store In Envelope

   When your tomato seeds feel dry and papery you’ll know they are completely dehydrated. Then, place seeds into an appropriately labeled sealable envelope for future plantings.

   If you are saving seeds from multiple different tomato varieties, place each variety into a different envelope and label it to avoid any mix-ups.

Storing Tomato Seeds for Future Use

Tomato seeds can stay viable for up to 10 years when fermented, dried, and stored in a cool, dry place. You can store them in your refrigerator or freezer in an airtight container for extra protection.

Fermenting the tomato seeds isn’t the only way to preserve them. You can omit the fermentation steps and simply clean and dry the seeds. If you dry your tomato seeds without fermenting them, they will only last 1 to 2 years. This is a good seed-saving option for those who plan to use their seeds quickly.