Kale was “king” in the 2010s. It is still a popular raw or cooked leafy green, since it is nutritious and easy to grow in the home garden. The key to getting the most return from the time invested in growing vegetables is choosing the correct cultivars and the proper planting date.
Common kales
Kale is one of the “leafy greens” in the plant genus Brassica. The three main types look very different in color and leaf shape, probably because they originate from three distinct regions in Europe.
Curly kale, sometimes called Scotch kale, is widely grown in northern Europe, including Scotland, the Netherlands and northern Germany. The edges of the leaves are ruffled and curled upwards. The color is a bluish green, and a few cultivars have reddish-purple leaves.
“Winterbor” is a productive curly kale cultivar suitable to grow most of the year in South Carolina.
Anna Mothersbaugh/Provided
Lacinato kale is called Tuscan kale because it is native to central Italy. The bumpy leaf texture is why this kale is called dinosaur kale. The leaves are narrow and grow upright. In Italian, Tuscan kale is “black cabbage” because its color is a dark green. A colleague from Italy told me it is traditionally used in Tuscan minestrone soup.
Siberian kale, as the name implies, is native to Siberia. “Red Russian,” the most common Siberian kale, has dull green, pointed leaves, while the leaf stem (or petiole) is reddish purple.
Recommended cultivars
My list of recommended cultivars is based on two years of research at the Clemson Coastal Research and Education Center in Charleston.
“Winterbor” curly kale was the best performer overall of the five curly kales we tested. It produced the greatest weight of healthy, edible leaves — even when exposed to black spot, a common fungal leaf disease on kale and other Brassica vegetables. Despite its name, Winterbor was especially productive in the spring.
The red curly kale tested, “Curly Roja,” was the least productive kale overall. The main reason to grow a red-leaved curly kale is to make a colorful mix of leaves, not for yield.
“Oldenbor” curly kale was more susceptible to black spot than the other kales. This cultivar, however, is highly resistant to yellows, a serious disease on kale grown during the summer caused by a soil fungus. The only reason to grow Oldenbor is for an early fall planting in September when the warm soil favors the parasitic fungus over the host plant.
“Red Russian” is the best Siberian kale cultivar. The red leaf veins add color to salads.
Anna Mothersbaugh/Provided
The three lacinato kales were very similar, so any of them can be grown successfully in South Carolina. Note that lacinato kale is more susceptible to white mold than curly kale. White mold is a cool-season disease that appears after the first frost. Curly kale is more suitable for an overwintered crop than lacinato kale is.
“Red Russian” is a popular Siberian kale for good reason. It yielded as much as any other Siberian kale but had fewer leaves with black spot. The related cultivar, “White Russian,” however, was susceptible to black spot.
Two other Siberian kale cultivars — named simply “Siberian” and “Siberian Dwarf” — were the most productive Siberian kales and yielded more than all curly kales except Winterbor. Their leaves grew tiny, sharp hairs when they were mature, which might make them unpleasant to eat. (I didn’t sample any.) Siberian kale, however, could be harvested for baby kale leaves in a salad before hairs develop. Overall, Siberian kales were the fastest growing type of kale.
Planting date
Kale grows well in South Carolina eight months of the year: March through June for a spring garden and September to December for a fall garden. July and August are too hot for this cool-season vegetable. January and February are too cold for active growth, and temperatures in the low 20s will damage kale leaves.
Kale can be directly seeded or transplanted. For salad greens, sow seeds one inch apart. For cooking greens, space plants one foot apart. Kale will grow in a part-sun to part-shade spot to save room in a sunny spot for fruiting vegetables.
Leaves of any age can be harvested. Cut the lower leaves and leave the top three or four leaves to grow larger for a second harvest.