Kohlrabi

About Kohlrabi

Kohlrabi is a cabbage relative grown for its swollen, round stem that sits just above the soil. It is quick, crunchy and mild, a bit like a sweet broccoli stem or a juicy turnip.

Grown as a cool-season annual in every zone; time it for the cool weather of spring or fall. More than a week of nights below 50F can make young plants bolt.

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

• Start seeds indoors: 8 to 10 weeks before the last frost
• Set out plants: 4 weeks before the last frost
• Sow seeds outdoors: 2 to 4 weeks before the last frost
• Fall planting: 12 to 16 weeks before the first fall frost

Days count from seeding or transplanting: about 35 to 45 for spring varieties and around 60 for large fall types, which need about 12 inches between plants. Start transplants 4 to 6 weeks before setting them out.

Soil

Loamy, well-drained soil high in organic matter; heavier or sandy soils work if drained and watered well.

Work in compost or well-rotted manure (up to about 1 inch), follow a soil test for phosphorus and potassium, and aim for soil pH 6.0 to 7.5.

Feeding

• 3 weeks after transplanting, or after thinning seeded plants (about 4 inches tall): nitrogen fertilizer such as 21-0-0. Use about 1/2 cup per 10 ft of row, 6 inches from the plants, and water it in.

If you worked in plenty of manure or compost you may not need more fertilizer; skip extra phosphorus unless a soil test calls for it.

Harvest

Cut the stem below the bulb when it is 2 to 3 inches wide; bigger bulbs turn tough, woody and bitter (giant fall types are the exception).

Cut each plant once when the bulb is 2 to 3 inches wide; bigger bulbs turn tough and woody. Sow in spring and again in July for a fall crop, which can grow a bit larger.

Varieties (12)

Extension sources document 12 kohlrabi varieties; Winner, Kossak, Waldemar and Gigante are listed by name with little description.

Good neighbors

Arugula, Mustard greens

UMN Extension says arugula and mustard can work as trap crops that draw flea beetles away from cabbage-family plants; this is a pest-trapping tactic, not a guarantee.

Pests to watch for

Flea beetles, Imported cabbageworm, Cabbage looper, Diamondback moth, Cabbage maggot, Swede midge

Diseases and problems

Black rot of cabbage-family crops, Clubroot, Alternaria leaf spot (cabbage family)

In the kitchen

Peeled and eaten raw in slaws and snacks, or roasted, steamed or stir-fried.

Keeping it: Trim off the leaves and refrigerate bulbs; they keep about two weeks. Use the leaves within a few days.

Pets: Not listed as toxic by the ASPCA