Kohlrabi (Brassica olereacea, gongylodes group) is part of the Brassicaceae family which are also called "Brassicas," "crucifers," and "cole crops". This family also includes broccoli (Brassica oleracea, italica group), Brussels sprouts (Brassica oleracea, gemmifera group), cabbage (Brassica oleracea, capitata group), cauliflower (Brassica oleracea, botrytis group), kale, and collards (both Brassica oleracea).
For more growing tips on vegetable varieties, visit our Vegetable Growing Guide.
Habit: Upright leaves above ground and large, round "root" (technically, the edible portion is an enlarged stem) half above and half below soil.
Days to Harvest: 38 to 45
When to Plant: Direct-sow in the garden in spring and sow successively until hot weather arrives; it can be sown again in late summer for fall harvests.
Light: Full sun
Soil: Well-drained soil amended with compost.
Watering: Keep well watered. Mulch helps keep roots cool and moist during hot weather.
Fertilizing: Regular fertilizing with a liquid fertilizer at half strength is helpful, especially with broccoli, cabbage and cauliflower, which are best grown quickly.
Pest Problems: Cabbage loopers and imported cabbageworms are voracious caterpillars that can make alarmingly short work of the leaves. Their color camouflages them on the plant perfectly, so you'll notice their damage before you find them. The use of floating row covers from planting time to harvest means that the adult moths cannot access plants to lay eggs; you can also spray plants with hot pepper or garlic spray, but this must be done at the appropriate time. Check with your state's extension service to find out when the pests emerge in your area. Slugs are also fond of broccoli (part of the Brassicas family). Handpick them at night, or trap them with beer or soda in a saucer nestled into the soil overnight.
When to Harvest: Quick-maturing varieties don't keep well, so pay close attention to sowing and maturity dates and begin checking the plants at the projected harvest date. Harvest when stems are well rounded, firm, and juicy. Overly mature kohlrabi will develop a pithy core.
For complete growing instructions of each vegetable in the Brassicas family, please see our individual growing guides below.