How to Harvest Cabbage Seeds

First Year: Grow Cabbages for Seed Production

• 1

  Choose the varieties of cabbage you would like to save seed from. Check to be sure they are open-pollinated varieties, not hybrids; seed saved from hybrids will not grow the variety you started out with.

• 2

  Plant at least six of each variety that you intend to save seed from. This ensures the genetic vigor of the next generation of plants. Space individual plants 2 feet apart. Once they are flowering in their second year, the plants will be quite large -- up to 4 feet tall -- and require that much distance between them.

• 3

  If you choose to grow more than one variety of Brassica oleracea, separate each variety by at least 1,000 feet. This prevents cross-pollination and ensures that the seeds you harvest will grow true to the parent plants.

• 4

  Place a thick layer of mulch around the plants in the fall. Make sure the mulch is at least 3 inches deep, but do not bury the plants. The mulch gives the roots some protection, but it is fine that the plants will be exposed to cold winter temperatures. Most cabbages require several weeks of temperatures near or below freezing in order to flower and produce seed in the spring.

Second Year: Collect and Store Cabbage Seeds

• 5

  Wait until the seedpods are tan or brown before collecting them. Seeds from green, immature pods are not viable.

• 6

  Place the seedpods in cloth or paper bags and store at room temperature for one week. This ensures that they are fully dry.

• 7

  Lightly crush the seedpods while they are still inside the bag. Save the seeds and discard the chaff.

• 8

  Store cabbage seeds away from direct light or heat. They will remain viable for up to four years.