First, let's get one thing out of the way: there is ornamental kale, and there is culinary kale. Both are members of the brassica family, but they're not quite the same. The ornamental kale (also known as flowering kale) has been bred to look like a pretty, colorful cabbage, which makes sense since they're related. Ornamental kale is still edible, but you probably wouldn't enjoy it much, as the plant is fairly tough and chewy.
And, to confuse things a bit, there are some culinary kales which are just so darned pretty, they're sold as ornamentals. With its upright habit, tightly curled leaves and deep purple color, 'Redbor' is probably the most stunning variety of kale you will ever see - and it's also edible. (And, as I can attest, it is an extremely tough plant. The 'Redbor' pictured at left has been growing in one of my vegetable beds for over a year -through one of Texas' worst droughts - and it is as gorgeous now as it ever was. Whether it has maintained its flavor remains to be seen.)
For the purposes of this article, we're going to focus on the types of kale commonly preferred for eating.
Kale has earned the ranking of a "superfood" due to its nutrient-per-calorie score of 1,000 on the Aggregate Nutrient Density Index. It boasts a hefty dose of Vitamins K, A and C, and magnesium, calcium and iron (thus the "new beef" designation.) Being a leafy green, it is also high in fiber. (See Nutritional Facts on Raw Kale.)
Edible Kale Varieties
Because of its increased popularity, gardeners should have no trouble finding seeds of the most popular kale varieties. There's the extra-curly Scottish 'bor' series, which includes the aforementioned 'Redbor,' 'Starbor,' 'Ripbor,' and 'Winterbor.'
'Lacinato' (aka 'Dinosaur' or 'Nero di Toscana') is a gorgeous blue-green Italian heirloom that dates back to the eighteenth century. A shorter but similar blue-green popular variety is called 'Dwarf Blue Curled Scotch.'
'Red Russian' (shown at right) features purple-tinged, flat, toothed leaves that are much tenderer than the curly varieties. Originally from Siberia, this variety was brought to Canada by Russian traders around 1885. 'Vates' also comes from Eastern Europe but resembles its more heavily-ruffled Scottish cousins. 'Vates' is acclaimed for its tolerance to both heat and cold.
A Portuguese kale called 'Beira' is also available but, while much more cabbage-like, it is not nearly as cold-tolerant as either cabbage or other kales. Its primary purpose is as an ingredient in Portuguese kale soup.
A new kale-broccoli cross is now available too, cleverly dubbed "Brokali." Burpee offers a variety called 'Apollo' that sports regular broccoli heads and stalks accompanied by kale-like leaves. Another similar type is 'Atlantis.'
If you choose to grow your own kale from seed, you can treat it much like you do cabbage. Seeds can be started indoors in late winter or direct-sown in the garden four weeks before your last average frost in early spring. For those in milder climates with a longer growing season, another crop can be started in late summer.
Larger varieties should be spaced three feet apart, while dwarfs can be closer. Kale generally takes 50-60 days to mature. Like other members of the brassica family, it can be targeted by cabbageworms, so be sure to check for caterpillars and chewed leaves periodically.
Kale grows best in rich soil supplemented with compost. And, because you want good leaf production, periodic applications of a nitrogen-rich fertilizer can also be beneficial.
Using and Storing Kale
Although kale is part of the cabbage family, its growth habit is more like lettuce in that you can harvest individual leaves or the entire bunch. Most kale will develop new leaves after you clip a few.
Unwashed, raw kale will keep in the refrigerator for about a week. To freeze, blanch and store in airtight plastic bags.
Understandably, the young, inner leaves are better suited for raw eating, while tougher outer leaves are better for steaming or added to cooked dishes. This is especially true for the thick-leaved types.
Many people don't like the bitter overtones in the taste of kale which, for the most part, is a lot like chard or collards. A light frost will sweeten kale's flavor, so harvesting after a frost is ideal if you can plan that well.
Recipes for Kale
Bobby Flay's Sauteed Kale
Crispy Kale "Chips"
Kale, Swiss Chard, Chicken, and Feta Salad
Kale and White Bean Soup
"Eat More Kale"
Believe it or not, kale has recently been at the center of a rather public legal controversy. About ten years ago, Vermont t-shirt maker Bo Muller-Moore designed a logo for a couple of farming friends featuring the phrase "Eat More Kale." In 2006, this caught the attention of fast food company Chick-fil-A, which uses the slogan "Eat Mor Chikin" to promote its (admittedly delicious) chicken sandwiches. In its initial cease-and-desist letter, Chick-Fil-A alleged that "Eat More Kale" would somehow confuse Chick-Fil-A customers and dilute their business.
Muller-Moore has ignored the warnings and continued to battle publicly with the food maker for the past five years. An online petition supporting the "Eat More Kale" cause is available and currently hosts nearly 25,000 signatures. Vermont Congressman Peter Welch recently threw his support behind the kale campaign by sending a letter to Chick-Fil-A Founder and CEO S. Truett Cathy, encouraging the company to leave the t-shirt maker alone.