How to Make Tomato Seed Tape from Dried Seeds
You can make your own tomato seed tape when saving tomato seeds.
It’s easy, it saves time during the drying process, and it makes planting time much more convenient.
The key is to dry seeds on paper towels or paper napkins. Seeds stick to the paper while drying.
You can roll up the paper towel, store, and save to use in the spring. Then, when it comes time to start seeds indoors, cut paper and moisten it for planting.
The seed will germinate and the paper will break down in the soil.
How to make tomato seed tape
Follow the basic method for saving tomato seeds as outlined below. Take special note of how to place seeds on paper towels or paper napkins when drying (step #5) to make tomato seed tape. Then, read what to do at planting time. You’ll see how easy saving, drying and planting your own tomato seeds can be – especially with seed tape, which saves time (not to mention that tomato seed tape makes it super-easy to handle those pesky, tiny seeds).
Step #1: Choose tomatoes
Save seeds from “open pollinated” (OP) or heirloom tomatoes. These tomato varieties are true to their type from their own seed, which means the next season’s plants maintain the same characteristics as they previous one. Hybrid tomatoes, on the other hand, are bred from two different varieties. Because of that, fruit from saved hybrid tomato seeds is unpredictable. Select your tastiest and healthiest heirloom (OP) tomatoes from which to save seeds.
How to choose tomato varieties from which to save seeds
Step #2: Extract seeds
- Slice the tomato in half on its equator
With a spoon or your finger, scoop out seeds. Place them in a bowl, cup or jar. Reserve the remaining tomato to eat fresh or use to make salsa.
- Add enough water to the tomato seeds and pulp (depending on the juiciness of the tomato) to make a soupy consistency. Stir the mixture to loosen the pulp from the seeds.
- Cover the container with plastic wrap (punch holes in wrap so air can move) or cheesecloth. If using a jar, punch holes in the lid or don’t screw it on too tightly. Air circulation helps fermentation. Fermentation causes air to expand. A tightly-fitted lid on seeds could make the container explode during fermentation.
- Label the container with the name of the tomato variety. Don’t trust your memory!
- Set the container in a warm, protected area, such as on top of the refrigerator or dehumidifier. The ideal temperature for fermenting seeds is 70º-80º F. Try to avoid drafty areas. If your house is cool, or you can’t find a warm area, seeds will still ferment but the process may take a day or two longer.
Step #3: Ferment seeds
The key to this step is close observation. Watch carefully to see when fermentation begins.
- Each day, remove the covering from the container. Stir the seed liquid. Replace the cover. Set the container back in its warm area. Repeat for 2-7 days (on average 4-5 days), depending on the temperature of your house and the area in which seeds are placed to ferment.
- As the mixture ferments, it will turn darker and emit odor. Look for three additional signs of fermentation:
- seeds separate and sink to the bottom of the cup as you stir
- a white, foamy mold will form on the top. The mold is harmless to the seeds. In cooler temperatures, mold may not form.
- bubbles start to rise to the top of the container
- Fermentation helps dissolve the gel casings around the seeds. Remove seeds from the liquid as soon as fermentation begins. If you allow seeds to stay in the liquid as it ferments, they may begin to sprout. Warm, wet conditions in the jar are perfect for sprouting seeds – a development you want to avoid when saving seeds.
Step #4: Rinse seeds
There are three purposes to rinsing: you want to stop the fermentation process, separate the pulp from the seeds, and separate the good seed from the bad.
- Remove foamy mold from top of container.
- Rinse seeds. Add water to fill the container. Stir the mixture several times and then wait about 10 seconds. Good seeds will sink to the bottom of the container; bad seeds will float to the top. Pour off the liquid and bad seeds.
- Repeat the rinsing process as many times as you need until all pulp, mold, and debris is rinsed from the seeds, all remaining seeds have settled to the bottom of the cup, the water is clear, and no seeds float to the top of the cup. It’s important to continue to rinse the seeds in the container in order to separate out bad seeds as they float to the top.
- When seeds are thoroughly rinsed and sorted in the container, pour them into a thin-gauged wire mesh sieve to wick out remaining water.
Step #5: Dry seeds on paper
Monitor seeds carefully to make sure they dry thoroughly before you store them.
- Spread rinsed seeds in a single layer of paper towel or paper napkin. Seeds will stick to the paper, becoming tomato seed tape. Allow at least 1 inch between seeds. This way, when they germinate, you will not have to thin them.
- Label paper towel or paper napkin with variety and date.
Set seeds in a warm area to dry, away from direct sunlight, such as on top of a refrigerator.
- Seeds will dry in 1-2 weeks.
- Seeds have difficulty drying in high humidity and high temperatures. If exposed to those conditions during the drying process, wet seeds may sprout.
- Do not heat seeds as they dry. Never place them in an oven.
Step #6: Store seeds
- When seeds are dry, roll up the tomato seed tape (paper towel or paper napkin).
Label seeds with variety and date.
- Add silica gel packets to saved tomato seed tape as an additional moisture deterrent and to increase shelf life.
- Store seeds in a cool, dry place. Many gardeners store tomato seeds in the refrigerator or freezer.
At planting time
Unroll your tomato seed tape (paper towel or paper napkin). Decide whether to plant the entire sheet or napkin as is, or cut it apart and plant seeds individually.
Place tomato seed tape, or cut pieces of the "tape," in a flat or cells filled with seed starting mix. Cover with ¼” layer of additional mix or perlite. Keep mixture moist. Paper towel or paper towel will break down as seeds sprout.
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By Kathy Widenhouse, award-winning writer and owner of Tomato Dirt, a leading online source for growing tomatoes and using them.
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