Purple cabbage is a striking and nutritious vegetable, recognized for its vibrant color and various health benefits. It is a popular choice for both home gardeners and culinary enthusiasts, adding visual appeal and a unique flavor to many dishes. This brassica, known scientifically as Brassica oleracea var. capitata f. rubra, is a rewarding plant to cultivate.
Identifying a Full-Grown Purple Cabbage Plant
A full-grown purple cabbage plant presents distinct visual characteristics. The most prominent feature is the development of a dense, solid head. When gently squeezed, a mature head should feel firm and compact, indicating it is fully formed. This firmness is a more reliable indicator of maturity than size alone.
Mature purple cabbage heads typically range from 6 to 8 inches in diameter, though some varieties can grow larger, sometimes reaching up to 15 to 18 inches. A ready-to-harvest head often weighs 2 to 4 pounds. As the plant matures, its color intensifies, developing a deep, vibrant purple hue. The outer wrapper leaves may show signs of wear or yellowing while the inner head continues to develop and remain protected. Visual cues remain the most dependable sign of maturity, though typical growing seasons range from 70 to 100 days from transplanting.
Key Factors for Optimal Growth
Achieving a healthy, full-sized purple cabbage head depends on providing specific environmental conditions and consistent care. Purple cabbage thrives in full sun, requiring a minimum of six to eight hours of direct sunlight each day. Adequate sunlight is important for vibrant color and robust growth.
The plant prefers well-draining, fertile soil rich in organic matter. An ideal soil pH for purple cabbage is slightly acidic to neutral, typically ranging from 6.0 to 7.0, which helps prevent certain diseases and ensures nutrient availability. Consistent moisture is crucial, especially during head formation. Aim for about one inch of water per week, ensuring the soil remains moist but not waterlogged.
Incorporating compost or well-rotted manure into the soil before planting can provide a good base of nutrients. During the growing season, a balanced fertilizer, such as a 10-10-10 blend, can be applied every two to three weeks, with attention to nitrogen during early growth and balanced nutrients as the head forms. Sufficient spacing is important, typically 18 to 24 inches apart, to allow for full head development and good air circulation.
When and How to Harvest a Mature Head
Harvesting purple cabbage at the right time ensures the best quality and flavor. The ideal time to harvest is when the head is firm and dense, having reached its mature size. Delaying harvest too long can lead to the head splitting, particularly after heavy rainfall.
To harvest, use a sharp knife to make a clean cut at the base of the plant, just below the head. Leave a few outer wrapper leaves attached to protect the inner layers if storing the head. After the main head is removed, the remaining stalk in the ground may produce smaller, secondary heads.
Do not wash purple cabbage before storing. It can be kept in the refrigerator for several weeks, often up to two months, ideally in a crisper drawer or a plastic bag to retain moisture.