Cabbage is a rewarding cool-season vegetable that offers a substantial harvest for the home gardener. Growing this crop from seed provides the opportunity to select from a wide range of varieties not typically available as transplants at garden centers. This method also allows for precise timing, which is important because cabbage thrives in moderate temperatures and bolts, or produces flowers, if exposed to prolonged heat. Successfully growing cabbage begins with mastering the specific steps of seed starting, transplanting, and providing attentive early care.
Determining the Planting Schedule
The first step in a successful cabbage harvest involves identifying the proper timing for your growing season. Cabbage is a hardy plant that performs best in temperatures between 60°F and 65°F, making it suitable for both spring and fall crops. The planting schedule revolves entirely around your area’s last spring frost date and first fall frost date.
For a spring harvest, start seeds indoors six to eight weeks before the last expected spring frost. Seedlings can be transplanted into the garden about two to three weeks before that frost date, as young plants tolerate light frost. Starting early allows the heads to mature before summer heat arrives, which can cause them to loosen or split.
For a fall crop, which often yields sweeter cabbage, the process is reversed. Start seeds indoors 12 to 14 weeks before the first anticipated fall frost. Transplant the seedlings approximately 10 to 12 weeks before that frost date. Direct sowing is generally less successful because the mid-summer soil is often too warm for optimal germination and early growth.
Step-by-Step Seed Starting
Sowing cabbage seeds requires attention to temperature and light to develop strong, stocky seedlings. Start by using containers, such as seed trays or peat pots, filled with a sterile, moist seed-starting mix. This medium reduces the risk of fungal diseases like damping off, which is a common threat to seedlings.
Sow the seeds shallowly, covering them with only about 1/4 to 1/2 inch of the growing medium. The ideal temperature for germination is around 70°F, which can be achieved with a heat mat if necessary. Germination typically occurs quickly, often within five to eight days.
Once the seedlings emerge, immediately place them under a strong light source, such as a grow light, positioned just a few inches above the plants. Simultaneously, reduce the ambient temperature to a cooler 60°F to 65°F to prevent the plants from becoming leggy or spindly. Maintain consistent moisture by using a fine mist sprayer or by watering from the bottom of the tray to keep the soil moist but not waterlogged.
Moving Seedlings to the Garden
The transition from the protected indoor environment to the garden requires acclimation known as hardening off. This procedure gradually exposes the seedlings to harsher outdoor elements like wind, direct sunlight, and fluctuating temperatures. Starting seven to ten days before transplanting, move the trays outside for a few hours daily, ideally in a shaded location.
Over the course of the week, progressively increase the duration of outdoor exposure and the intensity of the light, slowly moving the plants into direct sunlight. This allows the plant’s cuticle—the waxy protective layer on the leaves—to thicken, preparing it for the full sun and wind of the garden. Reduce the frequency of watering during this period, but avoid letting the plants fully dry out.
When the seedlings have developed four to six true leaves and are four to six inches tall, they are ready for transplanting into the garden bed. Plant the seedlings at the same depth they were growing in their containers to avoid burying the stem. Proper spacing is necessary for head development, typically requiring 12 to 24 inches between plants, depending on the variety and desired size of the mature head.
Essential Care for Young Cabbage Plants
Once transplanted, young cabbage plants require consistent moisture and specific nutrients to establish their root systems. Water the newly set plants thoroughly immediately after transplanting to settle the soil around the roots. Cabbage has shallow roots and requires one to two inches of water per square foot each week to maintain soil moisture.
Maintaining consistent soil moisture is important because fluctuations can lead to the mature heads splitting later in the season. Mulching around the base of the plants with a layer of straw or shredded leaves helps to conserve moisture and keeps the root zone cool. This practice also helps to suppress weeds, which compete with the cabbage for water and nutrients.
Cabbage is a heavy feeder, particularly requiring nitrogen for its large, leafy structure. About two weeks after transplanting, a light application of a balanced fertilizer can be beneficial. This should be followed three weeks later by a nitrogen-rich formula to support vegetative growth. Regularly inspect the plants for early signs of common pests, such as tiny, shot-hole damage from flea beetles or the chewing damage left by cabbage worms.