SEED SAVING CABBAGE SEED

Vernalization [cold period] required to induce flowering

Flowering occurs 2nd year

Vernalize in storage [below 50°] for 10-12 weeks in cold weather areas where plants won't survive in the garden over winter.

Population sizes

Seed Savers Exchange suggests saving seed from at least 5 plants to ensure viable seeds; or 20-50 plants to maintain variety over many generations; or 80 plants for genetic preservation of a rare variety;

Suzanne Ashworth said the basic general rule is that seed should be saved from 100 outbreeding plants – cabbages are outbreeding plants;

Pollination

Insect or hand pollination; most are self-incompatible

Isolation distance to avoid cross pollination

Up to 1 mile [Seed Savers Exchange: 800’-.5 miles]

Vernalization in Storage

Before the first frost, dig up the entire plant, roots and all. Trim off outer leaves but keep the cabbage head intact. Replant these trimmed plants into containers filled with slightly moist potting mix or sand or store heeled into sand or sawdust. Suzanne Ashworth recommends for the Northeast: dig  plants in early October; store heeled into sand or sawdust in a root cellar; roots should be watered mid-to-late winter. 

Replant cabbage in early May. When growing for seed, increase spacing to 18-24 inches apart in rows that are at least 36 inches apart. Second year plants can grow to 4 or 5 feet tall with many side branches, so staking is recommended to keep branches off the ground (SSE). She also recommends row covers for 2nd year plants – until flowers form; the 2nd year plants are extremely susceptible to flea beetles and animals.

Assessing Seed Maturity

After flowering in their 2nd year of growth, mature seed pods become dry and turn brown as the seeds inside also mature and brown. The window of time for an optimal harvest may be short as mature pods will begin to shatter and bird predation can become a problem.

Harvesting Seed

Seeds can be gathered by cutting entire branches or by harvesting whole plants. Because of this species’ tendency to shatter, the harvested material should be placed on drop cloths or in containers to prevent seed loss.

Cleaning and Processing

Branches of mature fruits can be threshed by rubbing the pods between one’s hands or by flailing the brittle pods against any surface that will cause fruits to break open. If the pods are dry, they will release their seeds easily when threshed.

Seed Storage and Viability

Store cabbage seeds in a cool, dark, and dry place in an airtight container to keep out moisture and humidity. Properly stored cabbage seeds will remain viable for several years.

Notes:

Seed shatters easily