Saving Tomato Seeds
Updated: Sep 7, 2022
If you’re interested in saving seeds, but aren’t sure where to start, tomatoes are a simple way to jump into the world of seed saving. But beware, once you get started, you might get addicted!
Before we jump into how to save seeds, there are a few things to consider. First, what kinds of tomato plants do you have growing right now or what kind are you planning to grow? One type, or a variety? Heirloom, open-pollinated, or hybrid?
If you have one type of tomato growing in your yard, great, you won’t have to worry too much about cross-pollination from other plants. If you have a variety, you may end up with seeds that contain traits of the other tomato plants and that could result in a hybrid tomato when you plant those seeds. But don’t worry, there are ways you can prevent cross-pollination. I’ll cover that in just a moment.
Another thing you want to keep in mind is heirloom verses hybrid verses open-pollinated. If you planted a hybrid variety, the seeds you save may result in a slightly different plant than what you currently have no matter what you do to prevent cross-pollination. This is because hybrids carry traits of the tomato varieties, they are hybrids of, so the seeds may produce a tomato that has stronger characteristics of one of those varieties over another.
Open-pollinated tomato seeds come from plants pollinated by insect, bird, wind, humans or other natural means. One of my favorite resources for seed saving is seedsavers.org. This is how they describe open-pollinated plants:
Because there are no restrictions on the flow of pollen between individuals, open-pollinated plants are more genetically diverse. This can cause a greater amount of variation within plant populations, which allows plants to slowly adapt to local growing conditions and climate year-to-year. As long as pollen is not shared between different varieties within the same species, then the seed produced will remain true-to-type year after year.
Heirloom tomato seeds are seeds that have been passed down from generation to generation and extra care has been taken to keep them from cross-pollination so they stay the same year after year.
Here are a few ways we can prevent cross-pollination to ensure the seeds we save will give us the same tomatoes we're growing right now.
Only plant one variety of tomato in your garden at a time. If you have close neighbors who also have tomatoes, you may still encounter cross-pollination issues though.
You could plant the tomato variety inside and hand pollinate the flowers.
Or another option is to watch for the blooms. Before the flowers open, place a mesh bag over them. When the flowers open, remove the bag, hand pollinate the flowers, and replace the mesh bag until you see the fruit growing.
When to save seeds
You’ll want to keep the tomatoes on the vine until they are a little overripe and slightly squishy to the touch. Pick the biggest and most impressive tomatoes for saving seeds from. If you’re only growing one variety of tomato in your garden, you can mark the tomatoes you want to save seeds from by tying a piece of yarn or string lightly around the branch connected to that tomato. This would also work if you planted indoors and want to use some tomatoes for eating and some for seed saving.
If you’re using the mesh bag option, you’ll want to hand pollinate a number of tomatoes, so you have several to choose from when the time comes. Before removing the mesh bag, make sure to mark the tomatoes so you don’t forget which ones you picked for seed saving.
Fermenting the seeds.
When you cut open a tomato, you might have noticed the seeds have a gel coating surrounding them. This gel coating prevents the seeds from germinating, so in order to save the seeds for growing more tomato plants, you have to remove the gel coating from them. This is done through a simple process called fermentation.
Gently wash your tomatoes to get any dirt and bacteria off it that could possibly impact the quality of your seeds.
Cut open the tomato and squeeze the seeds and pulp into a glass jar. You don’t want the skin or meat of the tomato in the jar.
Cover the seeds with water, put a lid on the jar and shake it. You don’t need to fill the jar.
Set the jar in a room temp location. You don’t want it to get too warm as this can cause mold to grow.
Each day for the next 3-5 days, remove the lid to let any gas escape, replace the lid and shake the jar. This will help the gel release from the seeds. You’ll notice the pulp will start to float to the top. I like to scoop off whatever is floating on day three, add a little more water, give it a good shake, and see how the seeds are looking. You’ll be able to see if there is any remaining gunk on them or not as long the water is clear enough.
When the fermentation is done, scoop of everything that floats, add more water until the jar in nearly full, replace the lid and shake it. Let everything settle for about an hour. Whatever seeds are sitting on the bottom of the jar are your viable seeds. Seeds floating on top are no good, dispose of those.
Drain off most of the water, then repeat the process. This ensures your seeds are clean.
Finally, drain off the water and dry your tomato seeds.