What: Ornamental kale and cabbage
The activity: Midsummer start of ornamental kale and cabbage for late summer, early winter color splash in a cool season garden.
Why: Ornamental kale and cabbage (Brassica oleracea) are some of the most popular cool season annuals. They lend a completely different texture to an end-of-summer garden landscape. Foliage plants often get overlooked when it comes to flowerbeds and containers. This is especially true during fall planting schemes. Ornamental (also known as "flowering" kale and cabbage) is one of the easiest bedding plants to grow, looks great all through the cool season, and is bothered by few pests. Ornamental cabbage and kale are great for replacing worn- out summer annuals or filling in an unexpected bare spot, for a long-lasting fall color display. The large plants cover a lot of space quickly for a small investment and require very little maintenance.
How to grow and use ornamental kale and cabbage effectively: Wait until temperatures start cooling down, then plant ornamental cabbage and kale in a sunny location in a moderately moist, rich soil. Bury stems so that the lowest leaves of the plants are flush with the soil surface. Plants at maturity can be as large as 12 to 20 inches across. Be sure to read instructions for spacing. The many varieties of white, pink, deep rose, purple, blue and lavender pigments will begin to develop when temperatures dip below 50 degrees F. Once acclimated in a site, ornamental kale and cabbages can survive temperatures as low as 5 degrees F, so plants may last well into November and December.
Try to position plants to best expose their colorful centers. Use them in mass plantings, in mixed or single container plantings, and as edgings. They look beautiful in the front of a border, especially when combined with perennials that are at their peak in the fall, such as little bluestem grass (Schizacrium scoparium), tall, dark-leaved sedums (Sedum spp.) or asters (Aster spp.). For an easy and attractive container planting, place an ornamental kale or cabbage in the center of a container and surround it with pansies. Or try them with other plants that can tolerate light frosts, such as Swiss chard (Beta vulgaris var. cicia), snapdragons (Antirrhinum spp.), petunias (Petunia spp.) or chrysanthemums (Chrysanthemum spp.)
Where to get ornamental kale and cabbage: Although ornamental kales and cabbages do best in cooler temperatures, new hybrids are being cultivated that are suited for warmer climates and will not bolt. Start plants from seed in midsummer or purchase transplants at your local garden center. Sow seeds about six to 10 weeks before the expected date of the first frost in your area. Seeds must be sown and young plants kept under cool conditions to thrive. In most climates, this means plants should be started where the temperature can be controlled. Alternatively, you can place pots with seeds in a refrigerator for several days to encourage germination. In cooler climates, sowing seeds directly in the garden may be possible. Ornamental kale and cabbage seeds require light for germination, so seeds should not be covered with soil, but placed on top of the soil.
When purchasing ornamental kale or cabbage transplants, look for large, compact plants that are nearly or fully colored. Plants will generally not get much bigger after they are planted in the garden, particularly if the roots are pot bound. Therefore, be sure to buy appropriate-sized plants for the location where they will be used, even though bigger plants will cost more.
When you have questions, Colorado State University Extension has research-based answers. Call a master gardener volunteer at 520-7684 or email CSUmg2@elpasoco.com. Volunteers are available Monday through Friday from 9 a.m. to noon.