Crop of the Week: Kohlrabi

Kohlrabi, German for ‘cabbage turnip’ and often referred to as ‘space cabbage’, is one of the easiest to grow members of the cabbage family. The edible part is not the root, but the enlarged stem that develops into a bulb just above the soil.  It is available in green, purple and white varieties.  The round bulbs can be steamed, stuffed or stir-fried; added to soups, or sliced and baked. Raw kohlrabi is crisp, sweet and mildly tangy, making it a popular low-carb choice with vegetable dips, or in salads and slaws. The greens can be a nutritious addition to salads and stir-fries. Once you try kohlrabi you are likely to become a fan!

Plant Family: Kohlrabi is a member of the cabbage family (Brassica oleracea, Gongylodes Group), along with broccoli, cauliflower, kale, and mustard.  Members of this family should follow legumes in garden crop rotation.  Like other members of this family, it performs best in cool seasons.

How to Grow: For Spring planting in Zone 6, it’s best to start the seeds indoors, 6 weeks before the last expected frost (May 15 in Zone 6).  If you prefer to direct sow, seeds should be planted ¼ – ¾ inch deep one to two weeks before the last spring frost.  Direct sow in midsummer for a fall crop.  Keep in mind that kohlrabi needs 40 to 65 days (on average, check your specific variety) to harvest.  The plants need to be mature prior to the first frost date (October 15 in Zone 6) but can remain in the ground.  Plant seeds 6 to 8 inches apart with 10 to 12 inches between rows.  Or sow a line of seeds and thin seedlings when plants grow at least three true leaves, leaving 6-8 inches between each plant and 10-12 inches between rows.  

Kohlrabi prefers rich, well-drained soil in full sun.  For a tender and mild harvest, provide consistent soil moisture and avoid having the bulbs form in hot weather, which can make them woody or spicy like a radish.  Mature kohlrabi plants are frost tolerant and like many other cole crops, the cool weather will make the taste sweeter.

Container Friendly?:  Yes, kohlrabi is a good choice for container gardening.  Select a large enough container (at least 12-16” in diameter and 16” deep) and fill with a good potting soil mix that contains lots of nutrient-rich compost. Grow one plant per container.

Try This:  If you can’t use all of your kohlrabi at harvest, trim off the leaves and stems, wrap the bulbs in plastic and store them in your refrigerator or a root cellar for several months.

How to Harvest:  Kohlrabi is best when the bulbs are harvested when they are about 2 to 3 inches in diameter (unless you are growing an unusually large variety).  Once it reaches the desired diameter, cut the kohlrabi at the soil level with a sharp knife.  You can also harvest the tender green leaves of the kohlrabi plant as it grows. The small leaves, harvested when the plant is young, are tender and flavorful and can be used like spinach or collard greens.  Do not harvest more than 1/3 of the plant for greens if you plan to let the kohlrabi bulb grow - the plant needs enough leaves to continue to provide energy to the growing bulb.

Common Varieties:  Different varieties of Kohlrabi have different lengths of growing periods – anywhere from 42 to 80 days – so choose carefully.  For Spring planting, select your variety to ensure that the bulb is developed before the temperatures average greater than 75°F.  For Fall varieties, you can choose a variety that will be harvested after a frost has occurred. 

• Short season (40-50 days): Quickstar, Korist, Kohlibri
• Long season (70-80 days) and large (8-10” bulbs): Superschmelz, Kossack

Recipes:  Peel the outer skin from the kohlrabi with a paring knife.  The bulbs can be steamed, stuffed or stir-fried; added to soups, or sliced and baked.  Or try eating the bulb like an apple!   The kohlrabi greens can be sautéed in olive oil with garlic and/or shallot.  Optionally add a splash of white wine or sherry and season as desired.  Other recipes can be found here:

• Kohlrabi Slaw with Cilantro, Jalapeno and Lime (courtesy of feastingathome.com)
• Roasted Kohlrabi (courtesy of thespruceeats.com)
• Kohlrabi Fritters (courtesy of earlymorningfarm.com)