Ornamental Kale

Ornamental kale is grown mainly for its large, colorful rosettes of leaves rather than its flowers. It is the same species as cabbage, broccoli and cauliflower, but its foliage is much showier. The leaves come in white, red and purple shades, with the color strongest as temperatures drop below 50 °F (10 °C). Plants usually reach about 1 to 2 feet (30 to 61 cm) tall and wide, and they are biennials grown as annuals.

Ornamental kale does not tolerate summer heat, so timing matters. Start seed in mid-summer, or buy transplants, for a good fall show. Seed germinates at 70 to 75 °F (21 to 24 °C), but seedlings do best at 60 to 65 °F (16 to 18 °C) or a bit cooler. Across a wider range, seed sprouted in 10 to 14 days at 70 to 85 °F (21 to 29 °C). Keep seedlings in a cool environment until planting to help prevent bolting. Sowing indoors 4 to 6 weeks before planting out is one option. Raising seed is best suited to a greenhouse where the temperature can be controlled. Wait until temperatures start cooling down, then plant in a sunny spot, burying the stem so the lowest leaves sit flush with the soil surface. Plant them en masse, in borders, along walkways or in containers in a fall or winter garden. Buy plants at the size you want, since they generally do not grow much larger after planting, especially if the roots are pot-bound.

Keep the plants well watered in a moderately moist, fertile soil that drains well. Plants are cold tolerant, and once acclimated they can survive temperatures as low as 5 °F (-15 °C).

Cabbageworms, cutworms, aphids and slugs may damage these plants, though late-season plants usually have fewer pest problems than spring-planted vegetable crops. Plants set out in spring often bolt or decline in summer heat. Until it gets cool, the plants have little color.

Ornamental kale is bred for its looks rather than for eating. The leaves are edible, but they tend to be more bitter than edible cultivars, and their bright colors fade to gray when cooked.