With right timing, gardeners can get two crops of kohlrabi per season |

With right timing, gardeners can get two crops of kohlrabi per season

Jessica Walliser
The edible portion of kohlrabi is its above-ground stem.

Question: I got some kohlrabi in my farm-share box last year, and my family really enjoyed it. I have a little raised-bed garden in the backyard and would like to grow my own kohlrabi this season. How do I do it? Is it difficult to grow? I’d appreciate any information you can provide.

Answer: Kohlrabi was once a common vegetable because it could be stored in a root cellar or cool basement for long periods of time. It fell out of vogue for decades, but now kohlrabi is back, winning fans everywhere.

The crisp texture of kohlrabi is mildly sweet and reminiscent of its close cousin, cabbage. Kohlrabi can be eaten both raw and cooked and is chock full of fiber, potassium and vitamin C. The edible portion of kohlrabi is actually its swollen, fleshy, above-ground stem, despite the fact that it’s often called a bulb. Kohlrabi is delicious when sliced in salads, grated into slaws, prepared as breaded-and-fried cutlets and even tossed into stir-fries and soups.

There are two ways to grow kohlrabi. For an early spring harvest of this cool-season crop, start seeds indoors, under grow lights or in a bright window, about four to six weeks before our last expected spring frost. Seeds should be sown about a quarter-inch deep in a pot or nursery flat filled with sterile potting mix.

After the seedlings form their first true leaves, they can be separated and transplanted into cell-packs or small pots. These seedlings can then be transplanted outdoors into the garden as soon as the nighttime temperatures are consistently above 30 degrees. Space them 5 to 6 inches apart.

If you don’t have the time or inclination to start your kohlrabi seeds indoors, you also can grow this crop by directly seeding them into the garden.

As soon as the soil can be worked in the spring, usually in early to mid April, sow the seeds an inch apart at a depth of a quarter of an inch. Be sure to work an inch or two of finished compost into the planting area before sowing the seeds. You’ll need to thin the resulting seedlings to 4 inches apart when they reach about an inch tall. This will give the remaining seedlings plenty of room to grow.

Most kohlrabi varieties are harvested between 60 and 65 days after planting, although as soon as the “bulb” reaches the size of a tennis ball, it’s ready to be picked.

Because kohlrabi prefers cool weather, planting the seeds too late in the season results in a woody, dry harvest. But, it’s also possible to have a fall harvest of this crop. To grow late-season kohlrabi, sow more seeds into the garden in late July or early August. These will be ready to harvest in the autumn and early winter.

Some of my favorite kohlrabi selections include the red-skinned varieties ‘Delicacy Purple,’ ‘Blaril’ and ‘Azur Star,’ as well as the white-fleshed ‘Korridor’ and ‘Korist’ and the giant-type ‘Superschmelz.’

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is

Send your gardening or landscaping questions to [email protected] or The Good Earth, 503 Martindale St., Third Floor, Pittsburgh, PA 15212.

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