Cabbage is a cool-weather plant, technically a biennial, that is cultivated as an annual vegetable crop for its dense cluster of leaves. Although the plant typically completes its life cycle in two years, it is grown for only one season to produce the edible head for harvest. For nearly all common heading varieties, such as green, red, and Savoy cabbage, the direct answer is one main head per plant. This single-head development results from the plant’s specific biological structure, which directs its energy into a solitary central growing point.
The Fundamental Answer: One Head Per Plant
The reason a cabbage plant yields a single, large head lies in the structure of its shoot apical meristem (SAM), the primary growing tip located at the center of the stem. During the vegetative growth phase, leaves develop with an extreme inward curvature, causing them to overlap and tightly wrap around the SAM. This process channels the plant’s energy into forming a solitary, compressed terminal bud, which is harvested as the “head.” The outer leaves constrain the growth of the inner leaves, resulting in the dense, firm structure.
This formation is distinct from non-heading brassicas, like kale or collard greens, which produce a loose rosette of open leaves. The plant prioritizes the development of this single, central structure for nutrient storage. Once the main head is fully formed and harvested, the primary growth mechanism is removed, but the remaining stalk still possesses the potential for secondary growth.
Post-Harvest Yield: Secondary Growth and Side Shoots
While the plant produces only one main head, a secondary harvest of smaller heads is possible from the same plant. This regrowth is initiated by auxiliary buds located along the stem where the lower leaves attach. When the apical dominance of the main head is removed by cutting, these dormant lateral buds begin developing. The proper technique is to use a sharp knife to cut the main head about one to two inches above the lowest set of outer leaves, leaving the stalk and a few leaves intact.
Leaving these lower leaves on the stem is important because they continue to photosynthesize and provide the energy to fuel the new growth. Depending on the variety, small sprouts may emerge from the nodes along the exposed stem. These secondary heads typically grow to the size of a baseball or a fist, often weighing between 300 to 400 grams each. Although these smaller heads are looser than the primary yield, they are perfectly edible and can collectively yield a greater total mass than the initial single harvest.
The plant must be maintained with consistent water and protection from pests to support this subsequent growth. Growers may observe two to six smaller heads developing per stump. Thinning the sprouts to just two or three allows the plant to focus its energy, resulting in slightly larger secondary heads.
Maximizing the Single Yield
Since the primary goal is to produce the largest possible single head, several cultivation factors must be managed throughout the season. Proper spacing is a fundamental consideration, as each plant requires a significant area to develop its expansive outer leaves, which are the main photosynthetic engines. Spacing plants about 12 to 24 inches (30 to 61 cm) apart prevents competition for light and nutrients, which results in smaller heads.
Cabbage is a heavy feeder, requiring consistently high levels of soil fertility to support the rapid growth of its dense head. The plant has a high requirement for nitrogen, especially during the early stages of leaf expansion and head formation. Applying a balanced fertilizer, such as a 10-10-10 formulation, approximately four weeks after transplanting provides the necessary nutrient boost.
Consistent and deep watering is necessary for robust head development and is important to prevent head splitting. This condition occurs when a fully mature, tightly packed head suddenly takes up too much water after a period of drought, causing the pressure to split the head open. Harvesting at the correct time, when the head is firm and solid to the touch, is the final step in yield maximization. If a sudden heavy rain is anticipated, gently twisting the plant can sever a few small roots, which temporarily reduces water uptake and helps prevent splitting.