Have you ever wondered how cabbage plants make their seeds?
Cabbage, broccoli, brussels sprouts, cauliflower, kale and kohlrabi are all of the same species, Brassica oleracea, and have the same seeding and pollination habit. These plants produce a flower stalk that needs to be cross-pollinated (meaning a plant will not accept its own pollen) by insects.
The cabbage plant sends this flower/seed stalk directly out of the cabbage core. Home growers, unless they live in a very long growing zone, at some point, they will need to be selected at least three firm ready-to-eat heads and remove the plants, roots and all, and store in a root cellar, refrigerator or cold basement. Keep the roots damp and cold during the cold weather.
You would replant the plants, leaving two to three feet in between them. They will produce the seed stalk directly from the center of the plant. Since cabbage seeds ripen slowly and fall off immediately when they are ripe, you might want to either harvest the whole plant as the pods turn yellow or pick the dry pods when they turn brown.
When planted in the open garden – and if you are growing any other members of the Brassica family – you might be surprised what your seeds develop into since the plants can be cross-pollinated with broccoli, brussels sprouts, cauliflower, etc. But they might be interesting in flavor.