Ornamental cabbage, often called flowering cabbage or kale, is cultivated for its vibrant, colorful foliage rather than for consumption. It belongs to the same species as edible cabbage, broccoli, and cauliflower (Brassica oleracea). While technically edible, ornamental cultivars are bred for aesthetic appeal, resulting in a bitter flavor compared to culinary types. These plants provide color to the garden during colder months when most other annuals have faded.
Establishing the Plants
Ornamental cabbage is a cool-season biennial typically grown as an annual, so timing the initial planting is important for a successful fall and winter display. For a fall display, start seeds indoors around mid-July, about eight weeks before the planned outdoor planting date in late summer or early fall. Sow seeds a quarter-inch deep in a seed-starting mix and maintain a warm, bright environment (60 to 70 degrees Fahrenheit) for germination.
Once seedlings develop their first true leaves, transplant them into individual pots to continue growing indoors. Before moving them permanently outdoors, gradually expose the young plants to outdoor conditions over one or two weeks for hardening off. When transplanting, space plants 12 to 18 inches apart to allow for proper air circulation and accommodate their mature rosette size.
Optimal Growing Conditions
Ornamental cabbage thrives in rich, fertile soil that drains well. The soil should be slightly acidic, ideally within a pH range of 5.5 to 6.5. While plants prefer full sun for the best growth and color intensity, they tolerate partial shade, especially in warmer climates.
Keep the soil uniformly moist but never waterlogged; water when the top inch feels dry. Aim for about one inch of water per week through rainfall and irrigation combined. Apply a balanced fertilizer only once during the initial planting, as excessive feeding, particularly nitrogen, can cause legginess and inhibit the development of vibrant colors.
Managing Common Garden Issues
As members of the Brassica family, ornamental cabbages are susceptible to the same common garden pests as their edible cousins. Key insect threats include cabbage worms (larvae of the Cabbage White butterfly) and cabbage loopers, which chew holes in the foliage. Aphids are also frequent pests, congregating on the undersides of leaves and sucking plant sap, leading to leaf curling and yellowing.
Non-toxic control methods are effective since the plants are not grown for food. Handpicking larger caterpillars and slugs early in the morning is a simple mechanical control. For soft-bodied pests like aphids, use a strong spray of water to dislodge them, or apply insecticidal soap or neem oil. Ensure good air circulation and avoid overhead watering to prevent fungal problems like leaf spot and root rot.
Seasonal Display and Maintenance
The visual appeal of ornamental cabbage depends on the arrival of colder weather, which triggers the development of intense colors. The vibrant pink, red, or white pigments (anthocyanins) begin to accumulate when temperatures consistently dip below 50 degrees Fahrenheit. It takes two to four weeks of cool nighttime temperatures for the full, vivid coloration to become pronounced in the central rosette of leaves.
These plants are cold-tolerant and continue to provide color long after many other annuals have succumbed to frost, often surviving temperatures as low as 5 degrees Fahrenheit. They maintain their form through multiple light freezes and can look attractive even with a light dusting of snow. The display concludes when the plants begin to “bolt,” or send up a tall flower stalk, a natural process that signals the end of their ornamental use as temperatures rise significantly.