This year I let one of my Kale plants go to seed. It made hundreds of seed pods on one plant!!
Kale is in the Brassica family along with broccoli, brussels sprouts, cabbages, kohlrabi, mustard, turnip.
Typically considered cool weather biennial crops.
Saving seeds: Let your kale plants overwinter to allow the seed pod time to develop. In spring the flower heads will develop into seed pods. The branching pods can get quite large and may need to be propped up.
Allow time to develope and dry on the plant. Once the pods begin to dry and the inner seeds are light brown and firm, you can cut the branches off and put head first into paper bags. Leave in the bag until completely dry, about 1 or 2 weeks. Brassica seeds shatter easily. Just rub the seed pods with your hands and the seeds will fall into the bag. Separate from the shells and store seeds in a cool dry container.
If properly stored, kale seeds can last up to four years.