Cabbage is a common vegetable, yet the question of whether it produces seeds often causes confusion. The direct answer is yes, cabbages do produce seeds. This vegetable belongs to the Brassica genus (Brassica oleracea), the same species that includes broccoli, cauliflower, and kale. The confusion arises because the seeds are not found within the tightly packed, edible head that is harvested.
The edible head is a large, terminal bud, representing the plant’s vegetative structure in its first year. Since the plant is typically harvested before reaching its reproductive phase, the seeds remain unseen by the average consumer. Like its brassica relatives, the cabbage plant must complete a two-year life cycle before producing seeds.
The Biennial Life Cycle and Seed Production
Cabbage is classified as a biennial plant, requiring two full growing seasons to complete its life cycle from seed to mature seed. The first year is dedicated to vegetative growth, focusing on producing its extensive root system and the familiar, dense head of leaves. This head acts as a storage organ, accumulating the energy reserves needed for the subsequent reproductive phase.
The second year is triggered by vernalization, which requires the plant to undergo a prolonged period of cold temperatures. Cabbage plants must survive a cold winter, typically below 45°F for an extended duration, before transitioning to flowering. This chilling period signals the shift from vegetative growth to reproductive growth.
Once vernalization is complete and temperatures rise, the plant “bolts,” sending up a tall, thick flower stalk from the center of the head. This stalk, which can reach 5 to 6 feet, produces numerous small, yellow flowers. After pollination, usually by insects like bees, the plant forms seed pods, completing the two-year reproductive process.
Physical Characteristics of Cabbage Seeds
Cabbage seeds are contained within slender, elongated structures called siliques, which develop after successful pollination. These pods are characteristic of the mustard family (Brassicaceae) and form along the bolted flower stalk. As the seeds mature, the siliques change color from green to tan or brown and eventually dry out.
Each silique typically holds between 12 and 20 seeds arranged in rows. The seeds are quite small, round, and possess a smooth texture. Their color ranges from light brown to dark brown or black, depending on the variety. Cabbage seeds closely resemble those of other common brassicas, such as mustard and broccoli.
Starting New Plants from Seed
Starting new cabbage plants from seed is standard practice for commercial agriculture and home gardeners, offering control over the variety and timing of the crop. Cabbage is a cool-season crop, so planting timing is crucial to ensure heads mature before the heat of summer. For a spring harvest, growers typically start seeds indoors to give the plants a head start against the outdoor season.
Seeds are generally sown about six to eight weeks before the last expected spring frost date in the region. Sowing the small seeds about one-quarter inch deep in a sterile seed-starting mix provides the best environment for germination. Optimal germination occurs when the soil temperature is maintained around 70°F, but once the seedlings emerge, the temperature is lowered to the 60°F to 65°F range to encourage stocky, healthy growth.
Seedlings are ready to be transplanted into the garden when they have developed three to four true leaves and a robust root system. This transplanting typically happens two to four weeks before the last expected frost date, as the young plants are tolerant of cooler outdoor temperatures. Hardening off the seedlings—gradually exposing them to outdoor conditions—is a necessary step before placing them permanently in the garden to prevent transplant shock.