Cabbage is a leafy vegetable representing a specific cultivar group of the plant species Brassica oleracea. Though botanically a biennial plant that completes its full life cycle over two years, it is typically cultivated as an annual crop for its dense, edible head. Successfully growing this cool-season vegetable requires a careful approach to its distinct developmental stages, from initial seed germination to final maturation and harvest.
Starting the Cabbage: Sowing and Germination
For most climates, the cabbage life cycle begins by starting seeds indoors, usually six to eight weeks before the last anticipated frost date, though direct sowing is possible. Seeds should be planted about a quarter-inch deep in a sterile seed-starting mix, ensuring the soil remains consistently moist.
Optimal germination occurs when the soil temperature is maintained around 70°F (21°C), allowing seedlings to emerge within five to ten days. Light is not required for germination but becomes important once the sprout breaks the surface. Providing ample light for about sixteen hours a day prevents legginess. Once seedlings emerge, the air temperature should be reduced to around 60°F (16°C) to encourage robust growth before moving them outdoors.
Vegetative Growth and Transplanting
Before indoor-started seedlings are moved to the garden, they must undergo “hardening off.” This seven-to-ten-day transition acclimates the plants to outdoor conditions like direct sunlight, wind, and fluctuating temperatures. The process involves progressively increasing the duration the seedlings spend outside in a sheltered location, minimizing transplant shock.
Cabbage seedlings are ready for the garden once they have developed two to three true leaves, approximately four to six weeks after sowing. Proper spacing is necessary for maximum head size, with plants set 12 to 18 inches apart in rows separated by two to three feet. The large, sprawling leaves that develop during this period are known as “wrapper leaves.” These outer leaves are the primary photosynthetic organs, producing the energy the plant redirects toward forming the dense interior head.
Cabbage is a heavy feeder, requiring high levels of nitrogen during this vegetative phase. Gardeners must ensure consistent soil moisture, as the plant has shallow roots that need about one to two inches of water per week. Maintaining this steady supply of nutrients and water sets the foundation for a successful heading stage.
Head Formation and Maturation
The transition to head formation marks a significant shift where the plant ceases outward growth and tightly wraps its newly generated leaves around the central growing point. This dense, compact structure results from the inner leaves folding repeatedly. Optimal head development occurs between 55°F and 75°F (13°C and 24°C), as prolonged exposure to heat above 80°F can inhibit this process.
Consistent moisture is important during this phase, as an uneven water supply can lead to head splitting. If dry soil is followed by heavy rain, the inner leaves expand too quickly for the outer wrapper leaves to contain them, causing the head to crack. Gardeners can mitigate splitting by slightly twisting the mature plant, which severs some roots and slows water absorption.
Maturity is assessed by the head’s firmness and density. A head ready for harvest should feel solid and heavy when gently squeezed. Conversely, temperature stress, such as extended periods below 45°F, can trigger bolting—the premature formation of a seed stalk instead of a dense head. Applying high-nitrogen fertilizer after the head begins to form can also lead to loose heads and increased splitting risk.
Harvesting and Storage
Cabbage is harvested by using a sharp knife to sever the stem just below the base of the head. It is recommended to leave a few lower wrapper leaves attached, as these provide natural protection against bruising and moisture loss during handling. A technique for a secondary yield involves cutting the head while leaving four or five outer wrapper leaves and a portion of the stem intact. This remaining stump can produce several smaller, loose heads for a later harvest.
For short-term preservation, freshly harvested cabbage maintains quality for several weeks in refrigeration. For long-term storage, conditions must be cold and moist, with optimal temperatures near 32°F (0°C) and high relative humidity (95% to 100%). This environment allows certain storage varieties to remain fresh for two to six months. Heads should not be washed before storage, and the wrapper leaves should remain to protect the interior.