Kale is a biennial green-leafed plant that has come to be known as a modern super food both for it’s nutritional properties, it’s hardiness, and ease of growth. It’s also a plant that’s easy to propagate year-after-year by saving kale seeds, and it takes very little time.
Step 1: Grow Kale!
It’s hard to save kale seeds if you don’t have plants.
Grow some kale. Alternatively you can befriend another gardener that already grows kale and–once you’ve lured them into a false sense of security–chloroform them, huck their body into a wood chipper, them assume their identity and ownership of their kale plants. Mwahahaha!
Don’t be shy about harvesting leaves from the plant throughout the growing season, but as you approach the fall season select the plants you feel had the best production, and let them run wild and “go to seed.”
Step 2: Collect the Pods
As your kale matures it will form pods called siliques: structures that holds the seed until they become viable. That’s fancy-talk for “capable of growing a new plant.” At the end of the season the pods become brittle and eventually break open, allowing the the seeds to escape and find a new space to grow in.
The pods are ready to remove after they’ve become brown, dry, and brittle but before they’ve cracked open and lost their seeds. Basically if the pods are still green it’s too early, but if the pods no longer exist it’s too late.
When the seeds are ready to harvest, just snip them off with scissors or shears and catch them in a bowl as you go.
Step 3: Separate the Seeds from the Chaff
We need to separate the seeds from the chaff, or seed casings. There are a lot of ways to do this step, but I’ve found that winnowing works very with kale seeds.
Crush the Pods
First locate a pillowcase, an old sheet, or any other thin cloth. Dump the pods you collected into the center of the cloth and fold it in half.
Next you need to crush the pods, and there are a lot of ways you can do this. You can use a rolling pin, a wine bottle, or anything else round and heavy and just roll it over the pods until the crushing sound stops being so obvious. You can also just walk back and forth over the cloth full of pods and eventually achieve the same result.
Winnow the Seeds
Winnowing is the process of blowing air over across the seeds to separate them from chaff. It works because the chaff is larger and easily caught by the air, while the seeds are too small and aerodynamic for a light breeze to have much affect.
Move your crushed-up pods from the cloth into a bowl. Shake the bowl in a circular motion. The seeds will naturally start to separate to the bottom. As you shake the bowl, blow a light current of air into it. Start very lightly and gradually increase the air pressure until the broken pods begin to take flight and leave the bowl. Eventually you’ll be left with what is almost entirely kale seeds!
Step 4: Cleaning and Storage
You can clean your kale seeds but it’s not necessary. If you’re concerned you might also be saving garden germs or plant viruses from year-to-year, soak your seeds for about 20 minutes in 120 degree water. You’ll probably render some of your seeds no longer viable, but you’ll also kill off most of the nasties that could be clinging to them.
Once your seeds are dry, store them in an air-tight glass or plastic container and save them in the freezer until next year. I like to label a paper envelope, put the seeds within it, and then put the envelope in an air and water-tight plastic container.