Cabbages are an important vegetable to grow at home, especially for winter and spring when few other fresh greens are available. By choosing different varieties you can be cutting cabbages all year round. Lightly steamed they are delicious and can even be eaten raw in coleslaw and salads.
I. Appearance and Characteristics
Brassica oleracea is a plant species from family Brassicaceae that includes many common cultivars used as vegetables, such as cabbage, broccoli, cauliflower, kale, Brussels sprouts, collard greens, Savoy cabbage, kohlrabi, and gai lan.
Its uncultivated form, wild cabbage, native to coastal southern and western Europe, is a hardy plant with high tolerance for salt and lime. However, its intolerance of competition from other plants typically restricts its natural occurrence to limestone sea cliffs, like the chalk cliffs on both sides of the English Channel. Wild B. oleracea is a tall biennial plant that forms a stout rosette of large leaves in the first year. The leaves are fleshier and thicker than other Brassica species—an adaptation that helps it store water and nutrients in its difficult growing environment. In its second year, it uses the stored nutrients to produce a flower spike 1 to 2 metres (3–7 ft) tall with numerous yellow flowers.
A 2021 study suggested that the Eastern Mediterranean Brassica cretica was the origin of domesticated B. oleracea. Genetic analysis of nine wild populations on the French Atlantic coast indicated their common feral origin, deriving from domesticated plants escaped from fields and gardens.
II. How to Grow and Care
Sunlight
Like most plants, wild Cabbage must be spaced adequately to ensure each plant receives enough sunlight on all above ground plant plants and to ensure that disease is unable to take hold. The majority of Brassicaceae will thrive in around 6 hours of direct sunlight each day. The plants should be positioned in full sun though care should be taken to ensure that they are protected from wind.
Temperature and Humidity
Ornamental cabbage and kale don’t develop their full colors unless they get a good chill from a frost. They can last throughout the winter, but their appearance depends a lot on the weather. If it’s hot with long daylight exposure, they will bolt (send up a flower stalk and go to seed). And if it’s very wet with harsh storms, the plants will quickly become tattered. They can survive as long as temperatures remain above 5 degrees Fahrenheit. However, a sharp drop in temperature can damage or kill plants.
Humidity typically isn’t an issue for these plants. But if the weather is damp and the plants don’t have good air circulation, they might develop fungal diseases, which usually appear as spots on the leaves.
Watering
Keep the plants well-watered; they like soil that’s consistently moist but not soggy. If the top inch of soil is dry, it’s time to water. If your climate provides regular rain, you probably won’t have to water at all. But be prepared to add supplemental water during a dry spell. Like many plants, about 1 inch of water (rainfall and/or irrigation) is perfect for these plants, but try to avoid overwatering.
Soil
Wild Cabbage grows best in firm, fertile and naturally-draining soils. Areas to be planted should be dug over in the preceding fall, with stones removed and well-decomposed manure or compost worked in ready for the growing season. Growers can also tread on the soil area to ensure that air pockets have been removed and the surface made adequately firm. In terms of pH, all families of Brassica grow best in soils just below neutral at 6-7 except for collards and mustards which enjoy slightly more acidic soils and cabbages that will tolerate slightly alkaline soils up to a pH of 7.5.
Fertilizing
Fertilize ornamental cabbage and kale only at planting time using a balanced fertilizer. Don’t fertilize while they’re growing, or they can lose color and get leggy.
Planting Instructions
Propagation of wild Cabbage seedlings is best started indoors with seeds planted six to four weeks before the last frost in spring or, for a winter crop ten to twelve weeks before the first frost in the fall. The seeds should be sown to a depth of a 1.3 cm. Once germinated, seedlings can be thinned to 8 cm between each plant. They can be transplanted once a height of 6 cm has been reached; for Brussels sprouts and kale, the height should be about double this. Spacing then depends on Brassicaceae but ranges from 30 to 76 cm.
Pruning
The large, thick low-lying leaves characteristic of many brassicas call for fairly regular maintenance and occasional pruning to ensure that leaves touching the ground do not start to rot. As well as removing possible sites for diseases to take hold, it helps to ensure that the plant’s energy is directed towards healthier growth. Any yellow, flat-looking leaves can simply be torn off or pruned with scissors. Large, healthy leaves covering other plants can also be removed but should be eaten.
Propagation
These biennial plants are generally discarded before the second season when they flower and set seeds. But if you do allow them to remain in the garden to produce seeds, the seeds can be collected from the faded flower heads and replanted at the appropriate planting time. You can store the seeds in the freezer to preserve them for later planting.
How to Grow from Seed
For spring plants, cabbage or kale seeds should be started indoors about eight weeks before the last expected frost date. For fall display, start the seeds about July 1, then plant the seedlings into the garden in mid-August.
Start the seeds indoors in small pots filled with a seed-starter mix. Plant the seeds about 1/4 inch deep and keep the soil moist in a bright location at about 70 degrees Fahrenheit. The seedlings will emerge in 10 to 21 days, and the potted seedlings can be planted outdoors immediately after the last spring frost—or in mid to late August for fall/winter display.
Potting and Repotting
If you only want one or two plants, ornamental cabbages or kales often look more natural when grown in containers rather than scattered throughout a garden. They can make nice seasonal potted plants, much the way that potted pansies are used in the spring, and potted chrysanthemums in the fall.
Choose a container with ample drainage holes, and use an all-purpose potting mix. Nursery plants likely won’t grow much larger than they are when you get them, so you typically won’t have to worry about repotting into a larger container.
Overwintering
Ornamental cabbages and kales are usually not allowed to overwinter, since the second year of these biennial plants leaves them rather unattractive as they send up flower stalks. But most gardeners will leave them in place well into the winter since the leave rosettes remain attractive until repeated hard frosts finally cause them to wilt.
Pests and Diseases
Common Pests and Plant Diseases
Like many edible vegetables in the Brassica genus, ornamental cabbages and kales are quite susceptible to cabbage worms, cabbage loopers, flea beetles, caterpillars, thrips, slugs, and aphids.2 Hard water sprays can be used to dislodge many of these pests. A variety of pesticide dusts or horticultural oils designed for vegetables will also work on these pests. Cabbage and kale planted in pots may be less susceptible to pests and diseases than those planted in the garden.
Common disease problems include leaf spots, blackleg, black rot, and yellows.1 These are most likely to occur when conditions are damp.
Common Problems With Ornamental Cabbage and Kale
Though used ornamentally, these plants are essentially vegetables and thus are susceptible to many of the common vegetable diseases and the pets that love to feed on edibles. Some notable problems you may notice include:
Holes in Leaves
This is almost certainly the result of one or more of the various feeding insects that love all members of the Brassicaceae family. Cabbage worms, a variety of other caterpillars, slugs, and aphids all view kales and cabbages as favored dining. A variety of insecticidal soaps or chemical sprays can be used to control these pests, and since these plants generally won’t be eaten, you can be more liberal in your use of chemicals.
Black or Yellow Spots on Leaves
Spots rather than holes in leaves usually indicate a fungal or bacterial infection. These are more likely to appear in damp weather conditions. Maintaining good air circulation can reduce the likelihood of these diseases. Fungicides may help treat fungal diseases if applied early enough.
Ugly Tall Stalks Appear
An otherwise attractive cabbage or kale that suddenly sends up a sparse and rather ugly stalk is in the process of bolting—going to flower. Its career as an ornamental plant is now over, though you can allow it to continue growing if you want to harvest the seeds for establishing new plants.
III. Uses and Benefits
B. oleracea has become established as an important human food crop plant, used because of its large food reserves, which are stored over the winter in its leaves. It has been bred into a wide range of cultivars, including cabbage, broccoli, cauliflower, brussels sprouts, collards, and kale, some of which are hardly recognizable as being members of the same genus, let alone species.
IV. Harvesting and Storage
Harvesting of brassicas depends on family and variety. Summer cabbages cauliflower kohl and common broccoli can all be harvested from the end of summer whilst many others are good for picking in the fall or winter. Low growing brassicas such as cabbages should be harvested by cutting close to the ground level using a sharp knife. When harvesting cabbages the whole plant should be lifted to reduce the risk of club root. Broccoli should be harvested when flower shoots are well formed. Kale on the other hand can be harvested throughout the season on a frequent basis.
