Saving Heirloom Tomato Seeds

Judy Henninger
Adams County Master Gardener

I grew up on a farm in southwestern Wisconsin. My mother had a very big garden. I guess she had to because she had seven growing children to feed. We all had to help with the planting, weeding, and harvesting of the various vegetables. I learned a lot from that big garden in Wisconsin. Hard work pays off and mostly fresh vegetables cannot be beat.

Now that I’m married and have a home of my own, I also have a garden of my own. It’s on a smaller scale than the one I grew up with, but it’s my labor of love. It’s fun watching seeds sprout and become plants that produce great tasting vegetables.

Being a Master Gardener has opened the door to many new experiences, some successful and some not so successful. I have come out of my comfort zone and have been trying new gardening techniques. I became interested in growing Heirloom tomatoes (tomatoes that are grown from seeds that have been passed down from generation to generation). I have had a trial garden, at the extension office for the past two years, where I am comparing Heirloom to Hybrid tomatoes. My other goal was to select healthy fruit and save the seeds for the next year’s trial garden.

I saved seeds from the selected tomatoes that I harvested last year. I saved the seeds over the winter and started them in the spring (March). I am a novice when it comes to saving and starting seeds indoors and have more failure than success stories to share. But that’s another article.

I learned from my failure of last year and found a successful way to harvest and save the tomato seeds. I would like to share that process with you. (Please note, you should save only Heirloom seeds, not Hybrid. Hybrid seeds need to be purchased.) Take the "leap of faith" and step out of your comfort zone. Start this season. Choose your best ripened tomato and save those seeds. You will be surprised how easy and successful you can be. It’s a great feeling when you save the seeds, start them indoors in the early spring, transplant them in your garden, and watch them grow into delicious fruit ready to start the cycle all over again.

Saving Heirloom Tomato Seeds

1. Choose the best fruits from the best plants. Harvest seeds when the fruit is fully ripe.
2. Slice the tomato in half, in the middle of the fruit between the stem and blossom end. You will see the cavities containing seeds and gel. This gel is a germinator inhibitor.
3. Scoop out the seeds in their protective gel. Put them in a glass container or shallow glass bowl. Add some water to the seed/gel mixture to avoid evaporation of all of the moisture. You want the seeds to be sitting in liquid when they are done fermenting.
4. Label container. I place the container on a coffee filter. You can write the name of the fruit on it.
5. Place in a cool out of the way place to let it ferment.
6. Check every few days. Depending on conditions, your seeds could be done fermenting in a few days or a few weeks.
7. When the seeds are ready, the surface of the mixture should be covered with a white colored mold. Do Not Over Ferment. When you see mold covering the mixture surface, it’s time to clean the seeds and prepare them for storage.
8. Scoop off the mold and discard. Remove any chunks of mold or tomato debris that does not contain seeds.
9. Pour seeds into a colander or small strainer. Remove any bits of tomato by hand. You should be left with only seeds and some pulp.
10. Rinse the seeds thoroughly with cool water. Shake off excessive water.
11. Spread out the seed onto a plate or coffee filter. Label the plate or coffee filter. (I prefer using several coffee filters, because help absorb some of the moisture from rinsing the seeds and they are easy to label. When the seeds are completely dry, they can be folded up in the coffee filter.) Let them dry, check them often to make sure they are spread out evenly and not in a big clump.
12. When the seeds are dry, place them in an airtight container such as a Ziploc bag or small mailing envelope in a glass jar with a lid. Store the jar in a cool dark place over the winter season until it’s time to start the seeds indoors for the next growing season.