This Colorful Winter Staple Is No Weakling

Redbor kale by Carol Reese

Large, frilly, and dramatically deep purple, redbor kale (shown right) can be grown in the landscape or in container groupings. It is winter hardy. Photo by C. Reese, courtesy UTIA. Download image​

From the UT Gardens
October 2017 Plant of the Month: Redbor kale

Submitted by Carol Reese, UT Extension Western Region Ornamental Horticulture Specialist 

Redbor kale has become a “must-have” for winter containers and it’s becoming more common in garden centers. This stunning foliage plant came to my attention as part of a winter color display in the Chicago Botanic Garden, so that should tell you something about its ability to stand up to low temperatures. I’ve sought it out as one of the truly hardy winter cole crops.

Cole crops include many staples among the cool-season vegetables – cabbage, broccoli, brussel sprouts, and greens such as kale, chard, turnip, mustard or collards. Some are standards in cool-season vegetable gardens throughout Tennessee, and others have become part of the popular “ornamental edible” movement for their striking foliage, often seen combined with traditional winter pansies.

It pays to be particular about which cole crops to use in winter seasonal color beds and containers. Some will take just a few degrees of frost and a few can tolerate temperatures in the single digits. The “flowering cabbage” types of kale are among those that only tolerate a few degrees of frost before turning to mush. Look for those that survive and flourish throughout the winter, such as dinosaur kale, or Russian kales such as winterbor.

King among these survivors is redbor kale. Large, frilly, and dramatically deep purple, redbor kale has never shown a hint of suffering in the several winters I’ve enjoyed it in my pots in West Tennessee. Be aware that it will easily grow to 2 feet tall, though 30 inches is not uncommon, and each plant can be about that wide. So, place accordingly, in full sun or mostly sun. If the weather is warm enough for insects to still be active, redbor kale should be monitored for pests common to cole crops.

It’s my understanding that redbor kale is a truly delicious kale, with its sweetness enhanced by frost. So far, however, I have found myself unwilling to sacrifice the beautiful foliage. Perhaps this year I’ll give it a taste, as I saved seed from one in my pots when it bolted in the summer heat and have 50 small plants for my efforts. Seed is easily found online if the plants are not available in your area.

Redbor kale can be seen on display at the UT Gardens locations in Jackson and Knoxville.

The UT Gardens includes plant collections located in Knoxville, Jackson and Crossville. Designated as the official botanical garden for the State of Tennessee, the collections are part of the UT Institute of Agriculture. The Gardens’ mission is to foster appreciation, education and stewardship of plants through garden displays, educational programs and research trials. The Gardens are open during all seasons and free to the public. For more information, see the Gardens website:



Carol Reese, UT Extension Western Region, 731-425-4767,​