The growing season is coming to a close, and soon enough, you’ll be pulling tomato plants out of the ground in preparation for winter. However, before your crop is gone for good, make time to save seeds for planting next growing season. It’s a fairly simple process, but there are a few things you should know if you haven’t saved seeds before.

1. Save Only From Organic Plants

If you want to grow organic tomatoes in the future, the seeds need to come from organic plants. Plants that have been heavily fertilized or sprayed with pesticides have adapted to that way of living and could potentially have a harder time at survival if you plan to go organic next year. Choosing seeds from hardy organic plants will give you your best odds at growing a strong crop in the years to come.

2. Save Only From Heirloom Plants

By saving seeds from heirlooms, as opposed to hybrids, you’re ensuring that your new crop will take on the traits of the parent plant. In hybrids, you may get traits from either the male or the female plant or even a plant further back in the plant’s lineage. While you’ll surely get a tomato, what type of tomato it will be is more in question.

3. Ferment The Seeds Before Drying

Tomato seeds, as you may have noticed, are covered with a slimy gel, which is meant to protect the seed. This covering needs to be removed if it’s going to be planted, and the way you do that is by fermenting the seeds with the gel in a jar covered with a cloth for three to four days. When you start seeing a mold appear on the surface of the liquid, you can strain the seeds through a sieve to remove the liquid and prepare the seeds for drying. However, be sure to get to the seeds before they begin to sprout—once sprouted their viability is lost.

4. Dry Tomato Seeds Somewhere Dark & Ventilated

After fermentation, lay the seeds on a paper towel or mesh screen out of direct sunlight to dry for about one week. Afterwards, you can store the seeds somewhere dark and cool until you’re ready to use them next year.