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How to Plant, Grow, and Harvest Kohlrabi

Kohlrabi in garden 1
Kohlrabi stem and leaves
Kohlrabi stems and leaves

Kohlrabi is grown for its swollen base which is actually the plant’s stem. The globe-shaped base develops above the ground. Kohlrabi is a good choice for gardens that don’t have deep soils. Kohlrabi is a hardy biennial grown as an annual. Both the globe base and leaves can be eaten.

Kohlrabi is a hardy biennial grown as an annual. Kohlrabi has a swollen globe-shaped stem that makes it look like a turnip growing on a cabbage root. Stems can be white, purple, or green and are topped with a rosette of long-stemmed blue-green leaves. Kohlrabi is milder and sweeter than either cabbage or turnip.

Here is your complete guide to growing kohlrabi!

Kohlrabi Quick Growing Tips

  • Sow kohlrabi seed in the garden 3 to 4 weeks before the last average frost date in spring.
  • Kohlrabi grows best in cool temperatures between 40°F and 75°F (4.4°C and 23.9°C).
  • Kohlrabi requires 45 to 60 days to reach maturity. In warm winter regions, sow kohlrabi in late summer for winter harvest.
  • Kohlrabi can withstand an early autumn frost.
  • Kohlrabi yield: plant 4 to 5 kohlrabi per household member.
Kohlrabi seedlings
Kohlrabi seedlings

Where to Plant Kohlrabi

  • Plant kohlrabi in full sun.
  • Grow kohlrabi in well-worked, well-drained soil rich in organic matter.
  • Work 2 inches (5cm) of aged compost into the soil before you begin planting.
  • Kohlrabi prefers soil within the 5.5 to 6.8 range. Side dress kohlrabi with aged compost at midseason.
  • Indoor starting: Kohlrabi seeds can be started indoors or in a cold frame or plastic tunnel.

When to Plant Kohlrabi

  • Spring planting time: Kohlrabi is a cool-weather crop. Sow kohlrabi seed in the garden 3 to 4 weeks before the last average frost date in spring. Kohlrabi requires 45 to 60 days to reach maturity and should be grown so that it comes to harvest before temperatures average greater than 75°F (23.9°C). Grow kohlrabi for fall harvest in hot-summer regions.
  • Planting for fall or winter harvest: In warm winter regions, you can grow kohlrabi through the winter. Sow kohlrabi in late summer for winter harvest. Kohlrabi can withstand an early autumn frost. In cold winter regions, sow kohlrabi in summer for early autumn harvest.
  • Succession crops: You can sow kohlrabi seeds as long as temperatures are greater than 40°F  (4.5°C).

Kohlrabi Cold-weather Care

  • If you are growing kohlrabi for late fall or winter harvest, protect plants with row covers or a plastic tunnel if nighttime temperatures below 25°F (-4°C) are predicted.

More tips at Kohlrabi Seed Starting Tips.

Planting and Spacing Kohlrabi

  • Sow kohlrabi seed ½ inch deep and 1 inch (2.5 cm) apart; thin successful seedlings from 5 to 8 inches (12-20cm) apart.
  • Space rows 18 to 24 inches (45-60 cm) apart.
  • Thinned seedlings can be transplanted to another part of the garden.
  • Intensive spacing: Sow seed or set out transplants 4 to 6 inches (10-15cm) apart in a staggered double row.

How much to grow. Grow 6 to 10 plants per person.

Kohlrabi Companion plants

  • Grow kohlrabi with beets, celery, herbs, onions, and potatoes.
  • Do not plant with pole beans, strawberries, or tomatoes.

Container Growing Kohlrabi

  • Kohlrabi is large rooted and not well suited for container growing.
Kohlrabi in garden
Keep the soil evenly moist as kohlrabi grows to harvest.

Water and Feeding Kohlrabi

  • Keep soil evenly moist for quick growth. Kohlrabi that goes without water will become woody.
  • Prepare planting beds with aged compost.
  • Side dress kohlrabi with aged compost once a month. Alternatively, you can fee kohlrabi once a month with a plant-starter fertilizer or a balanced organic fertilizer.

Kohlrabi Care

  • Cultivate carefully to avoid harming the shallow roots.
  • Mulch kohlrabi with aged compost when plants are 4 to 5 inches (10-12 cm) tall.

Kohlrabi Pests

  • Kohlrabi can be attacked by cutworms, cabbage loopers, and imported cabbage worms.
  • Place collars around stems to protect seedlings from cutworm damage. Remove egg clusters from underneath leaves and wash plants with a diluted soap solution.
  • Cabbage worms can be controlled by spraying with Bacillus thuringiensis.

Kohlrabi Diseases

  • Kohlrabi is susceptible to cabbage yellows, clubroot, and downy mildew.
  • Plant disease-resistant varieties.
  • Remove and destroy infected plants.
Purple kohlrabi
‘Early Purple Vienna’ kohlrabi

Harvesting and Storing Kohlrabi

  • Kohlrabi is ready for harvest when stem globes reach 2 to 3 inches (5-7cm) in diameter.
  • Globes that grow larger than 3 inches (7.5cm) in diameter may become woody.
  • Kohlrabi leaves can be harvested for the table; cook them like you would other greens.
  • If the skin of a globe is tough, peel away the outer layer; the center may still be tender and flavorful.
  • Winter harvest. In mild-winter regions, leave kohlrabi in the ground over the winter and harvest globes as needed.

More tips at How to Harvest and Store Kohlrabi.

Storing and Preserving Kohlrabi

  • Kohlrabi will store well in the refrigerator for 1 to 2 weeks or for one to two months in a cold, moist place.
  • Kohlrabi can be peeled and diced for freezing.

Kohlrabi Varieties to Grow

  • Varieties: ‘Early Purple Vienna’ (60 days); ‘Early White Vienna’ (55 days); ‘Grand Duke’ (50 days); ‘Purple Danube’ (52 days); ‘Kolibri’ (50 days).
  • ‘Early White Vienna’ produces compact plants; light green skin and white flesh globes; this variety is slow to bolt; grow from seed in 50 to 55 days.
  • ‘Grand Duke’ produces green-skinned globes to 4 inches (10cm) in diameter; grow from seed in 48 to 50 days.
  • ‘Kolibri’ produces purple globes with white flesh; it can tolerate heat; grow from seed in 50 days.

About Kohlrabi

  • Common name. Kohlrabi, turnip-rooted cabbage, stem turnip, turnip cabbage, German turnip
  • Botanical name. Brassica oleracea, Gongylodes group
  • Origin. Hybrid

Grow 80 vegetables: KITCHEN GARDEN GROWERS’ GUIDE

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. Harvesttotable.com has more than 10 million visitors each year.

Comments

Comments are closed.
    • Companion planting is supported by the experience of gardeners and anecdotal evidence. Kohlrabi and melons are not typically considered companions. But, you can plant them close together and see what your experience is.

  1. I planted kohlrabi from seed very early in the spring when it was very cold. The seeds germinated great and made healthy looking little seedlings. I transplanted the seedlings in the garden, but now they will not grow. I started the seeds more than 60 days ago and the entire plant is only one inch. Why?

    • The plants’ roots may have been partially broken or disturbed interrupting growth and stunting the plants. Feed the plants with B1 Vitamin or a dilute solution of fish emulsion or kelp meal (get these at the garden center). In the meantime, plant a second crop where you want it to grow wo it does not need moving.

    • The best strategy is to take but the bulbous stem and roots and replant seed. This will allow you the most production from your garden.

    • Check the days to maturity for each cultivar. If the purples are shorter days to maturity, it may be accountable to temperature; if the temperatures have been warming. Another possible reason is a greater amount of nitrogen in the soil–or more nitrogen fertilizer–where the white kohlrabi is growing. It may take a bit of detective work–but it is like an environmental cause.

  2. I read commentre: flowering. I put in transplants from market mid may. Spikes yellow flowered, bulb large marble size. If I cut back stems can I leave for winter over. Or do
    I not trim back but leave for winter crop. Do I need thick leaf grass cover for this?

    • Kohlrabi is a cabbage-family cousin. It prefers cool weather although it will grow in warm weather–but it will need a lot of water. If the plant has flowered, it is past harvest time. Pull the plant and replant it in early spring or in early autumn. Kohlrabi is a fast grower; you can get a couple of crops in spring and fall. There is no advantage to letting it sit in the garden over the winter; harvest it when it is big enough to eat.

  3. Hi my cats have broken the stems and the leafs will these still grow as the bulb hasn’t developed yet. The stems are broken just above where the leaves split off on top

    • The kohlrabi “bulb” is a swollen stem; if the stem of the plant has been damaged it is unlikely the plant will go on to produce the swollen stem. Place stakes at the corner of the planting bed and drape bird netting over the stakes and bed to discourage the cats.

    • If the kohlrabi bulb has broken away from the lower stem, then it’s time to eat the bulb. If the water-conducting capillaries were broken the plant will quit developing. If by broken, you mean the bulb was cut or knocked, the bulb will continue to grow toward harvest.

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