Kohlrabi plants form bulbs, actually edible swollen stems, just above the ground that are shaped like round tennis balls. They are green or deep violet-purple depending on the variety, with ruffled foliage that looks like broccoli leaves growing out of the bulb's tops and sides. Many friends gaze in amazement when they first see my kohlrabi bed. Neighborhood kids have always called it my "flying saucer" or "space ship" vegetable. Yet anyone with a Slavic or Asian background smiles fondly and licks their lips because they know how tasty the crunchy mild flesh of these eccentric looking bulbs can be both raw and cooked.
Kohlrabi's name is a combination of the German words for cabbage and turnip, but to me, the flavor of the bulbs crisp flesh is sweeter than either of its family members. Peeled kohlrabi bulbs are juicy with a delicate sweet flavor that I would describe as a cross between apples and very mild baby turnips. Elizabeth Schneider, in her classic Uncommon Fruits and Vegetables (Harper and Row 1986), says that to her, kohlrabi tastes "like the freshest, crunchiest broccoli stems, touched with a hint of radish and cucumber."
The origins of kohlrabi are a matter of debate since some plant historians think it was cultivated as long ago as the Roman era, while others claim it was developed from the mallow cabbage as late as the 16th century. Although its antecedents may be obscure, kohlrabi is a very popular staple throughout Asia and Eastern Europe. In the USA, it is harder to find, but you can usually buy it in markets of many areas of the Midwest and Mid Atlantic states, or wherever there are heavy concentrations of German or Eastern European communities.
Crispy Colors Duo Kohlrabi
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Kohlrabi is a reliable, productive and easy growing ornamental edible to grow in cool spring weather and again in fall when summer heat tapers off. The tasty bulbs and leaves are good sources of vitamins C and A, calcium, potassium and fiber and they are low in calories, about 40 per cup. Like all brassicas, kohlrabi is a potent anti cancer vegetable. The biennial plants are very quick to mature, bulbing up quickly to harvest in just 60 to 70 days after planting. Newer hybrid varieties offer much more vigorous plants that grow rapidly and produce big crunchy bulbs without the pithy or stringy qualities that plagued older, more traditional kohlrabi cultivars.
Growing great kohlrabi is easy and rewarding. It needs a good rich soil, preferring a neutral to slightly acid pH. Prepare your garden bed for planting by digging in lots of well aged manure or compost. While you can grow a fine crop of kohlrabi by direct sowing, I prefer to set out young seedlings started indoors from seed no more than 5 to 6 weeks before the last expected frost date. I find that healthy, sturdy transplants are better able to survive lurking slugs or snails and unexpected inclement weather.
To start kohlrabi indoors, sow seeds about 1/2 inch deep and an inch apart in a container of seed starting mix. Keep evenly moist and provide a good light source. Germination takes 10 to 14 days and seedlings thrive in 65 to 75 degree conditions. When well established with at least one strong set of true leaves, thin seedlings to 3 or 4 inches apart or transplant them to deeper containers. Keep evenly watered and feed every 10 days with half strength liquid fertilizer. As soon as outside temperatures reach 50 degrees, acclimate seedlings to outdoor conditions for 4 or 5 days out of direct sun, then plant into the garden about 6 to 8 inches apart and water in well. Do not wait too long before transplanting your young seedlings as stressed or root bound kohlrabi will not produce good bulbs. In the garden, keep plants well weeded and evenly watered to ensure rapid development. Feed every three weeks or so with a balanced liquid fertilizer, compost tea, or fish emulsion and kelp solution.
Kohlrabi is not prone to serious pest problems, but to totally avoid predators and make my gardening easier, I usually cover the seedlings after transplanting with floating row covers which are permeable to both light and water. While they are not the most beautiful garden accessories, I find these row covers stabilize growing conditions and protect crops against any insect infestation. I remove them when plants are well established and beginning form baby bulbs, at about 6 to 8 inches tall. If you don't use row covers, a strong spray of water or insecticidal soap solution controls aphids or white flies and 2 to 3 inch cardboard collars averts cutworms. Non-toxic BT is an effective way to deal with cabbage moth larvae or other caterpillar pests. Limit disease potential in your garden by planting kohlrabi and all its brassica relatives in 3 year rotations.
I begin to harvest kohlrabi when they reach 2 to 3 inches in diameter. Cut the stem about an inch below the round bulbs. Trim off the leaves to cook separately and store the thick skinned bulbs in the vegetable crisper of your refrigerator. They will keep well for at least 3 weeks to cook up as you need them. I still enjoy kohlrabi sliced up raw best of all, but now I like to use both leaves and bulbs as cooked vegetables too. The leaves make a wonderful greens. Cut out and discard the stems, then drop the leaves into a pot of boiling salted water. Cook until just tender, about 3 to 4 minutes. Then heat some olive oil in a skillet, add garlic or chopped onion and sauté until fragrant and softened. Toss in the kohlrabi leaves and cook a few minutes more. Finish with a squeeze of fresh lemon. Peel and slice kohlrabi bulbs raw for snacks, just like you would slice up an apple. Thin slices make crispy sweet dip holders or can be used instead of crackers for creamy spreads. Slices are great to add to green salads instead of cucumbers. You'll find shredded raw kohlrabi makes especially mild, sweet coleslaw, and you can also make kohlrabi pickles.
Kohlrabi's mild flesh cooks up to tender sweet succulence. Peel off the outer skins and slice or cube to sauté slowly in sweet butter, or steam the unpeeled bulbs whole, then peel and cut up. Traditionally, cooked kohlrabi is served in a rich homemade cream sauce and it is quite delectable this way, especially with a few gratings of nutmeg added to the sauce. Stir fry kohlrabi with carrot slices, and scallions for a delicious and colorful side dish, seasoned lightly with fresh ginger root. I've found that cooked kohlrabi pairs beautifully with fresh herbs like lemon thyme, marjoram, summer savory, garlic chives, broad leafed parsley, or dill leaf and aromatics like curry, nutmeg, ginger or paprika. To finish a dish of herbed kohlrabi perfectly, add a dollop of sour cream or fresh, whole milk yogurt. Unpeeled, trimmed kohlrabi bulbs can also be baked in the oven. Just put them in a covered casserole with 2 to 3 tablespoons of water and bake at 350 degrees for about an hour or until fork tender. Cool, peel and slice, and dress with a little butter and lemon and your favorite herbs or spices as above. I find that baking the bulbs is easy and really seems to intensify and concentrate their flavor.
In choosing varieties of kohlrabi to plant, I have found that the newer hybrids rather than the older Purple Vienna and Green Vienna, which tend to get pithy and tough with size. Our fast-growing purple and green-skinned Crispy Colors Duo mix makes a pretty picture in garden beds. These extra-fancy hybrids rapidly size up into crispy bulbs with thin skins and crunchy, sweet, white flesh. The violet varieties have dark violet skins and leaves and pale flesh. While they do not keep their purple coloration when cooked, they are especially lovely in the garden. Plant a second crop of kohlrabi for fall eating once summer heat begins to diminish. You can start the seeds in a container outdoors in light shade, then plant out seedlings in the garden, shading them for a few days until they are established. Fall kohlrabi is an especially sweet and tender treat you'll savor as an end of the season gardening reward every year. Try some of these curious and delicious vegetables in your garden this season.
- 4 medium kohlrabi bulbs
- 1 T butter or margarine
- 1 T olive oil
- 1 clove garlic, minced
- 1 medium onion, chopped
- 1 T fresh lemon juice
- 2 T chopped fresh parsley
- Salt and freshly ground pepper to taste
- 2 T fresh low fat sour cream
Peel the tough outer skin from the kohlrabi, then coarsely grate bulbs. In a skillet heat butter and olive oil. Add garlic, onion and kohlrabi and sauté, stirring for 5 to 7 minutes or until kohlrabi is tender crisp. Stir in lemon juice, parsley, then season with salt and freshly ground pepper to taste. Stir in sour cream, and serve hot.
Serves 4 to 6
- 3 kohlrabi peeled and sliced 1/4 inch thick
- 2 large carrots peeled, cut into sticks, parboiled 3 minutes
- 2 cloves garlic, crushed
- 1 bay leaf
- 3 large sprigs fresh dill
- 3/4 cup white vinegar
- 1 1/4 cups water
- 3 T sugar
- 1 tsp mustard seed
- 1/2 tsp dill seed
- 1/4 tsp red pepper flakes
- 1 tsp salt
Combine kohlrabi and carrots and pack in a 1 quart glass jar along with garlic, bay leaf and fresh dill. In a saucepan combine pickling mixture ingredients and heat, stirring, until it boils and sugar is dissolved. Pour boiling mixture over kohlrabi filling jar completely. Cover jar. When cool, refrigerate for 3 to 4 days before using to let flavors blend.
Makes 1 quart