Jennifer Schultz Nelson
Extension Educator, Horticulture
The thought of fall annuals usually conjures up images of mums and perhaps pansies. Another often overlooked option is ornamental kale.
Ornamental kale is technically the same genus (Brassica) and species (oleracea) as the more familiar broccoli, cabbage, and other cole crops. It is also genetically the same as kale grown in vegetable gardens as an edible green. Ornamental kales were developed by plant breeders from edible kale varieties by selecting plants with unique foliage colors. Ornamental kales are still edible, but they are mostly used for garnishing cooked dishes because of their gorgeous color.
Ornamental kale is considered an annual, but botanically it is biennial, meaning its life cycle occurs over two years. The first year it produces vegetative (leafy) growth, and the second year it produces reproductive growth (flowers). Gardeners value it for its vegetative rather than reproductive growth, so practically speaking it is treated as an annual in the garden, being replanted each year.
Unlike most annuals planted in the garden through the growing season, ornamental kale thrives in cold weather. When the plants are acclimatized to the cold, they can withstand temperatures as low as five degrees Farenheit.
Light frosts occurring in October and November will actually intensify the typical blue-green outer leaves and brightly colored inner rosette typical of ornamental kale. These bright colors range from white, to pink, purple and even red.
When purchasing ornamental kale, be selective. To maximize their lifespan in your fall landscape, look for plants that are not rootbound or otherwise overgrowing their container. Choosing plants that are on the small side or appropriately sized for their container gives plants a great start and increases their chances of surviving well past the first frosts in the garden.
Sometimes ornamental kale is sold under the name "ornamental cabbage" which is not really correct. While both are brightly colored, ornamental cabbage will form a head just like edible cabbage and has broad smooth leaves, whereas ornamental kale will not form a head, and has deeply dissected, ruffled leaves.