These unusual members of the cabbage clan have shed their identities as vegetables and moved into flower beds, pots, and window boxes where they are appreciated for their frilly-edged, colourful leaves. These guidelines will help you learn how to use these cold-hardy, tough-leaved foliage plants to bring colour to fall and winter flower beds or containers, which is a trick that they can carry off quite well on their own or in combination with colour-coordinated blooms.
Flowering cabbages and kales are closely related and grown the same way, but there are differences in form. Flowering cabbages have broad leaves that form a flattened head, while the leaves of the kale types are heavily frilled. Leaves often start out green and then turn red, purple, pink, white, or a mixture of these shades, with the colour concentrated on the inner leaves. The hues deepen as the plants mature and the weather becomes steadily cooler.
By late fall, these plants are in their prime. The flowering kales in particular make wonderful accents in autumn window boxes and containers.
1. Colourful cabbage kings
Fast and reliable, the ‘Colour-Up’ hybrid flowering cabbages grow into loose, 30-centimetre-wide (one-foot-wide) heads with intensely hued red, pink, or white centre leaves. For contrast in texture, mix them with the frilly leaves of ‘White Peacock’ or ‘Red Peacock’ flowering kale.
2. Growing flowering cabbage and kale
You can buy plants at garden centres in the fall or start seeds indoors in summer, about 10 weeks before your first frost is expected.
- Plant seeds about one centimetre (0.5 inch) deep in moist seed-starting soil and keep the soil moist and at 18°C (64°F) until the seedlings are up and growing.
- Summer insect pests are likely to chew the leaves, so wait until the weather is cool to move the plants outdoors. Because flowering cabbages and kales are attractive to the velvety green caterpillars called cabbageworms, as well as to grey-green cabbage aphids, it’s a good idea to keep plants in 10 centimetre (four inch) pots on a table or bench, away from garden soil. There you can keep a close eye on them and treat invasions promptly by rinsing pests off leaves with a firm spray of water from the hose or applying insecticidal soap as the package directs.
- Set plants out after frost has ruined tender summer annuals and pests have all but disappeared. After nights have chilled below 10°C (50°F), expect the plants to quickly gain size, change colours, and enjoy excellent and care-free health.
- If winter temperatures suddenly take a downward plunge, flowering cabbage and kale can suffer badly. However, in years in which the plants can gradually become accustomed to cold, they often withstand temperatures that dip well below freezing, frequently surviving winters in Zone 6 and warmer areas. In the spring they will send up attractive spires of yellow flowers adding a dazzling finale to their long display.