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Kohlrabi
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Kohlrabi is a member of the
cabbage family. |
Kohlrabi, Brassica olearcea var. gongylodes, is
a hardy biennial member of the cabbage family. It was first recorded being
grown in northern Europe in 1554, and had reached North America at least
by the early 1800's. The name is a German word meaning cabbage (kohl)
- turnip (rabi), describing the turnip-like enlargement of the stem
above the soil (it is NOT a root vegetable). Leaves stand out like spokes
from the edible portion, the rounded stem section, which is commonly referred
to as a bulb (even though botanically it is not a bulb). Although it is
quite exotic looking, it is merely a different horticultural form of the
same species to which common cabbage, kale, broccoli, and cauliflower belong.
Its flavor is similar to that of turnips but milder and sweeter.
Varieties
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There are both white and purple-skinned
kohlrabi cultivars. |
There are a number of both "white" (really light green) and purple cultivars.
The purple types only have colored skin; the interior flesh is white. In
Europe, fancy varieties with frilled and deeply cut leaves are sometimes
grown as ornamentals. The number of days from planting to harvest is indicated
after each.
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'Early White Vienna' is a standard white variety with few leaves (55 days).
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'Early White Purple' is a standard purple variety with flattish, red-purple
(60 days).
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'Eder' is a tender and fast-maturing white type (38 days).
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'Express Forcer' is a white type with compact plants that hold up well
even in heat (42 days).
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'Gigante' is best for fall crops, producing an extremely large bulb up
to a foot in diameter and 25 pounds, that does not get woody (80 days).
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'Grand Duke' produces vigorous small plants that are tolerant of black
rot (45 days).
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'Granlibakken' offers excellent texture and sweet, mild flavor (45 days).
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'Kolibri' is a new deep purple Dutch hybrid that produces large bulbs (up
to a pound) with nearly fiberless white flesh (43 days).
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'Kossak' is another very large variety, producing bulbs up 10 inches across
with sweet, delicate flavor (70 days).
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'Logo' is a super-early white forcing type used in Europe for baby vegetable
production (45 days).
Culture
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| Grow kohlrabi in well-drained soil in full sun. |
Kohlrabi is easy to grow in full sun in moist, well-drained soil rich
in organic matter. Like other cole crops, they do best in cool weather,
but tolerates heat better than most other members of the cabbage family.
Sow seeds directly in the ground in early spring, as soon as the soil is
workable. For an earlier harvest, seeds can be started indoors 4-6 weeks
before transplanting outdoors when the ground is ready. For a continuous
supply through late spring and early summer, make small plantings every
2-3 weeks. Fall plantings should be sown in mid-summer. Plants are cold-tolerant
and will survive in the garden long after frost. Plan your planting so
harvest will be a week or two after the first fall frost is expected in
your area.
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Space kohlrabi plants 2-5 inches apart, or farther
for large varieties. |
Place seeds ¼-½" deep and thin the seedlings to 2-5" apart
(or more if you are growing one of the huge varieties). Keep the plants
well-watered, as abundant moisture will prevent the stems from becoming
tough and woody. Cultivate carefully to avoid damaging the shallow roots.
Fertilize before planting and again at midseason.
Pest Management
Kohlrabi generally has few insect or disease problems. Cabbage caterpillars
(imported cabbageworm, cabbage looper and diamondback moth) may infest
the plant, but their feeding on the leaves doesn't affect yield unless
populations are very high. These caterpillars can be controlled by hand-picking,
chemical sprays, or applications of Bacillus thuringiensis (Bt).
Yellows, clubroot, black rot and downy mildew are a few cabbage family
diseases that may affect kohlrabi but are not common in the home garden.
Plant disease resistant varieties when available and maintain vigorous
plants. Avoid handling the plants when they are wet and remove any infected
plants/plant parts.
Harvest
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Kohlrabi 'Gigante' produces
large bulbs that are not woody. |
Kohlrabi has the mildest and best flavor when small. Older kohlrabi
tends to be tough and woody and it may have an off-flavor – except
in some newer varieties, such as 'Gigante' and 'Kossak' that do not develop
woody fibers in the enlarged stem. You can begin harvest when the bulbs
are about one inch in diameter and continue harvesting until the bulbs
reach the mature size for that variety. Pull the entire plant out of the
ground, or cut it off at ground level.
To store kohlrabi for several weeks, remove the leaf stems and place,
unwashed, in sealed plastic bags in the refrigerator.
Serving Suggestions
Young kohlrabi leaves may be cooked like other greens. The bulbs can be
eaten raw in salads or can be cooked like a turnip. Very young, tender
bulbs can be used without peeling, but larger ones should be peeled. The
bulbs can be hollowed out and stuffed with a vegetable or meat filling.
The peeled flesh can be sliced, diced or grated and used in recipes calling
for radishes. If added to slaw, lightly salt it first, let stand for several
minutes, and squeeze to remove any excess water before adding dressing.
When steaming or boiling kohlrabi, peel after cooking.
Kohlrabi is a good source of vitamin C and potassium. It is low in both
sodium and calories. One cup diced and cooked kohlrabi contains only 40
calories and 140% of the RDA for vitamin C.
– Susan Mahr, University of Wisconsin - Madison
Additional Information:
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