Ornamental cabbage and flowering kale are known for their intensely colorful pigmentations. The color does not appear until after prolonged cool weather and a few frosts. They are a great bonus when all of fall’s usual flowers—asters, goldenrods, Sedum ‘Autumn Joy’, and even chrysanthemums are gone.
By Charleen Barr
Colorado State University Extension Master Gardener in Larimer County
Cabbage, broccoli, cauliflower, collards, and Brussels sprouts are all variants of the species Brassica oleracea. Cabbage is known as Bassica oleracea (Capitata group) and Kale is Brassica oleracea (Acephala Group). They are cool weather vegetables grown for harvesting of their edible leaves. Cabbage forms head and kale forms upright leaves.
By contrast, ornamental cabbages and flowering kales are grown primarily as foliage plants for their brightly colored leaves rather than as vegetables. Ornamental cabbage typically develops large rosettes of broad flat leaves and ornamental kale typically develops curly, ruffled leaves. The bloom is not a flower but rather the rosette of central leaves that lose their chlorophyll as the mercury drops, changing from green to white, pink, purple and red. Planting ornamental cabbage and kale in August or early September will allow the plant to become established, but if the temperature isn’t cool enough, this will result in a leggy, relatively colorless plant. Planting too early also means dealing with cabbage loopers, which bore unsightly holes through the plant.
Ornamental cabbage and kale may be grown from seed, but a better idea for most gardeners is to buy the plants, which are widely available at garden centers and nurseries in the fall. Most of these potted plants are root-bound and will not get bigger, so choose a good-size plant, not a small one. Place the cabbage and kale in a sunny location with moderately moist, rich soil. Bury stems so that the lowest leaves of the plant are flush with the soil surface. Keep the plants well watered until cool weather arrives, usually below 50 degrees F. Full coloration takes three to four weeks. The plants need to be almost full grown when coloring time arrives. Once acclimated to a site, ornamental cabbages and kale can survive temperatures as low as 5 degrees F.
A few popular cultivars include ‘Redbor’ with tightly ruffled, upright reddish purple leaves. The Nagoya series has large, round heads of ruffled leaves with bright purple, white or pink heads . There are the crinkle-edged types like Nogoya hybrid, feather-leaf types like Red Peacock, and round-leaf types like Tokyo hybrid. Each type may have a red, pink or creamy white center.
Ornamental cabbage and flowering kale look especially good in a large planting, where their color really stands out. Since they are low growers, they are often seen as edging plants, where their purplish hues blend in well with other fall colors. When using one or two plants, consider planting in containers, rather than scattering throughout a garden. In fact, they make nice, long lasting replacement plants for spent summer containers.
Ornamental cabbage and kale are edible, but to reduce their bitter taste, they need to be boiled, the water discarded, then either boil them again or sauté them in olive oil prior to serving. These ornamental vegetables are rich in dietary fiber, Vitamins A, C, K and B6, iron magnesium, phosphorus, calcium, and more. No flower can match that!
For more information, visit PlantTalk Colorado at www.planttalk.org and read #1821 on “Kale.”