How To Grow Kohlrabi – Growing Kohlrabi In Your Garden

Growing kohlrabi (Brassica oleracea var. gongylodes) isn’t the hardest thing in the world, as kohlrabi is actually somewhat easy to grow. Start your plants indoors about four to six weeks before you plan to put them outside.

How to Grow Kohlrabi

After four to six weeks, plant the baby plants outdoors in well drained, rich soil. Growing kohlrabi is most successful in cooler weather. The early crops started indoors and then transplanted outdoors will provide you with a nice crop.

When you think about how to plant kohlrabi, remember that there are many different types. Kohlrabi is a member of the cabbage family. There are white, reddish and purple varieties, some of which will mature early and others mature late. The Eder variety, for example, is a faster maturing variety that takes about 38 days to mature, while Gigante matures in about 80 days. Gigante is best for fall.

How Does Kohlrabi Grow?

When growing kohlrabi, most growth occurs in spring or in fall. The plant definitely prefers cool weather, so if you can only grow one crop a season, fall is preferred. It will taste best if it matures in the fall.

Kohlrabi isn’t a root plant; the bulb is the stem of the plant and it should sit just above the level of the soil. This part of the root will swell and become a sweet, tender vegetable you can cook or eat raw.

How to Plant Kohlrabi

When thinking about how to plant your kohlrabi, you have a choice to start it outside or inside. If you start it inside, wait until the baby plants are four to six weeks old before transplanting them into your prepared garden soil outside.

First, fertilize your soil and then plant the kohlrabi. You can have a continuous crop if you plant your kohlrabi every two to three weeks. Make sure to place the seeds ¼ to ½ inch deep into the soil and about 2 to 5 inches apart (5-13 cm.) if planting seeds directly outside.

Also, when growing kohlrabi, keep the soil well watered or you’ll end up with tough,woody stemmed plants.

When to Harvest Kohlrabi

Harvest kohlrabi is when the first stem is 1 inch (2.5 cm.) in diameter. Kohlrabi can be continuously harvested, up until the stems are 2 to 3 inches (5 to 7.6 cm.) in diameter. After that, your plants will be too old and too tough. As long as you know best when to harvest kohlrabi, you’ll have plants with a milder, sweeter flavor.

I have so many fond memories of my summers as a youth. Perhaps the most delicious is the memory of watching my Danish grandmother strip away the tough outside layers of a freshly-pulled kohlrabi.

She would then slice the inside flesh into circular “chips,” which she would serve to us with a sprinkling of salt.

This amazing treat was the reason for my insistence as an adult that we have kohlrabi in our own gardens. The lovely cabbage flavor and crisp, juicy texture is strikingly similar to the way the inside of a broccoli stem tastes.

It can even be difficult to distinguish a newly planted kohlrabi from its broccoli and cabbage cousins.

But this is where the similarity ends. The above-ground root plant focuses all of its plant energy into one large bulbous mass.

German for “cabbage turnip,” kohlrabi brings beautiful flavor in an easily harvested plant that is surprisingly resistant to insects.

Veggie Varieties

There are two basic variations of this plant.

The purple varieties are beautiful in color, both at the edible fleshy stem and in the luxurious leaves.

The white type is actually light green, and the type we are most accustomed to seeing in stores and at farmer’s markets.

Favored cultivars of the plant include:

Purple Vienna

This selection has beautiful leaves and is quite decorative. It can be used as a bright addition to any yard or garden.

Seeds are available from Mountain Valley Seed Co.

Grand Duke

This is a large-growing variety that outsizes many of the heirloom breeds. And seeds are available from Amazon.

It does well in a variety of conditions, and doesn’t get as tough or stringy at peak growth.

Early White Vienna

Best eaten when small, the pale flesh of this cultivar is tender and sweet!

You’ll find it at MV Seeds Co.

Proper Planting Tips

Kohlrabi loves cool weather and moisture, so ensure that the soil is slightly damp when you are planting the seeds.

I like to plant around the end of April, with plenty of time to grow before the weather gets too hot.

Most varieties take about 8 weeks from sowing to harvesting, so be certain that hot temps won’t arrive before it’s time to pick.

In The Victory Garden Cookbook, author Marian Morash recommends that a clump of seeds be spaced about 4 inches apart, then thinned to just one plant at each 4-inch interval.

The Victory Garden Cookbook, available on Amazon

I have found that one seed usually does well, though. And if I’m short on seeds, I plant one seed per hole at about 3 inches and still have a good harvest.

I push them just barely below the soil surface with my index finger before smoothing over with topsoil. The directions on the packaging will provide additional insight on best practices.

The Right Size for Picking?

Kohlrabi fans have had differing views on the right time to pick.

I have always been of the thought that “bigger is better” and like to see each plant give me as much food as possible.

Once harvested, it’s unlikely that you’ll see anything more come from that same plant – especially if you’ve reached hot temperatures for the season.

There are some, however, who love the smaller, sweeter bulbs, and prefer to pick at 1-2 inches across. These tiny treats are some of the most flavorful and sweet goodies I’ve had from a garden.

If you want quality over quantity, picking small certainly has its rewards!

Whichever you choose, note that the fibrous outside of the bulbs will likely need to be removed before eating.

You can cut the kohlrabi at the base, leaving the root in the ground, or pull the entire plant. If you want to continue to harvest leaves, you may want to choose the cutting method.

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About Linsey Knerl

Born and raised in a small Nebraska town, Linsey Knerl is a homeschooling mother of six who enjoys blogging and working hard on her 3 1/2-acre Nebraska homestead. When she’s not working on her next fantasy novel, you will find her in her kitchen, perfecting the Danish recipes of her grandmother with those special ingredients you can only find in a backyard garden.

Kohlrabi is a hardy biennial grown as an annual. 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.

Description. 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 is topped with a rosette of long-stemmed blue-green leaves. Kohlrabi is milder and sweeter than either cabbage or turnip.

Yield. Plant 4 to 5 kohlrabi per household member.

Kohlrabi seedlings

Planting Kohlrabi

Site. Plant kohlrabi in full sun. Grow kohlrabi well-worked, well-drained soil rich in organic matter. Kohlrabi prefers soil within the 5.5 to 6.8 range. Work aged compost into planting beds before sowing. Side dress kohlrabi with aged compost at midseason.

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). In warm winter regions, 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.

More tips at Kohlrabi Seed Starting Tips.

Planting and spacing. Sow kohlrabi seed ½ inch deep and 1 inch (2.5 cm) apart; thin successful seedlings from 5 to 8 inches apart. Space rows 18 to 24 inches (45-60 cm) apart. Thinned seedlings can be transplanted to another part of the garden.

Companion plants. Beets, celery, herbs, onions, potatoes. Do not plant with pole beans, strawberries or tomatoes.

Container. Kohlrabi is large rooted and not well suited for container growing.

Keep the soil evenly moist as kohlrabi grows to harvest.

Caring for Kohlrabi

Water and feeding. 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 at midseason.

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.

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 diluted soap solution. Cabbage worms can be controlled by spraying with Bacillus thuringiensis.

Diseases. Kohlrabi is susceptible to cabbage yellows, clubroot, and downy mildew. Plant disease-resistant varieties. Remove and destroy infected plants.

‘Early Purple Vienna’ kohlrabi

Harvesting and Storing Kohlrabi

Harvest. Kohlrabi is ready for harvest when stems reach 2 to 3 inches in diameter.

More tips at How to Harvest and Store Kohlrabi.

Storing and preserving. Kohlrabi will store well in the refrigerator for 1 week or for one to two months in a cold, moist place. Kohlrabi can be frozen.

Kohlrabi Varieties to Grow

Varieties. ‘Early Purple Vienna’ (60 days); ‘Early White Vienna’ (55 days); ‘Grand Duke’ (50 days); ‘Purple Danube’ (52 days);

Common name. Kohlrabi, turnip-rooted cabbage, stem turnip, turnip cabbage

Botanical name. Brassica oleracea, Gongylodes group

Origin. Hybrid

Grow 80 vegetables: KITCHEN GARDEN GROWERS’ GUIDE

Harvesting Kohlrabi Plants: How And When To Pick Kohlrabi

While kohlrabi is normally considered a less traditional vegetable in the garden, many people grow kohlrabi and enjoy the pleasing flavor. If you’re new to growing this crop, then you’ll likely find yourself seeking information about harvesting kohlrabi plants. When you want to know when to pick kohlrabi, it helps to learn more about the growing conditions of the plant.

Kohlrabi History and Appearance

Kohlrabi is in the same family as mustard and close relatives with cabbage, cauliflower, broccoli, kale and Brussels sprouts. The plant was grown first in Europe around 1500 and came to America 300 years later. It produces a swollen stem that has a broccoli or turnip type flavor and can be steamed or eaten fresh. Many people have questions about growing, caring for, and when to pick kohlrabi in the garden.

Growing Kohlrabi

Grow kohlrabi in a sunny location with rich, well-drained soil. Before planting, work at least 3 inches of organic matter into

the soil. Kohlrabi can be grown from seeds or transplants. Seeds should be planted ¼ – ¾ inch deep around one to two weeks before the last spring frost. Thin seedlings when plants grow at least three true leaves. Leave 6 inches between each plant and 1 foot between rows.

Planting every two to three weeks ensures a continuous harvest from spring through early summer. For a jump on the season, you can plant kohlrabi in a greenhouse and transplant as soon as the soil can be worked. Provide regular water, mulch for moisture retention and be sure to keep weeds to a minimal for best results.

How Long to Wait for Kohlrabi Harvest

You are probably wondering how long to wait for kohlrabi harvest. Fast growing kohlrabi grows best in temperatures 60 to 80 F. (16-27 C.) and is ready to harvest in 50 to 70 days, or when the stem reaches 3 inches in diameter.

Harvesting kohlrabi plants is best done when they are small. This is when the vegetable’s flavor will be the best. Kohlrabi left in the garden for a long time will become extremely tough and unpleasant tasting.

How to Harvest Kohlrabi

In addition to knowing when to pick kohlrabi, you need to know how to harvest kohlrabi plants. When harvesting kohlrabi, it’s vital to keep an eye on the swelling base. Once the stem reaches 3 inches in diameter, cut the bulb form the root with a sharp knife. Position your knife at soil level, just under the bulb.

Pull the leaves off of the upper stems and wash the leaves before cooking. You can use the leaves as you would cabbage leaves. Peel off the outer skin from the bulb using a paring knife and eat the bulb raw or cook as you do a turnip.

With right timing, gardeners can get two crops of kohlrabi per season

Question: I got some kohlrabi in my farm-share box last year, and my family really enjoyed it. I have a little raised-bed garden in the backyard and would like to grow my own kohlrabi this season. How do I do it? Is it difficult to grow? I’d appreciate any information you can provide.

Answer: Kohlrabi was once a common vegetable because it could be stored in a root cellar or cool basement for long periods of time. It fell out of vogue for decades, but now kohlrabi is back, winning fans everywhere.

The crisp texture of kohlrabi is mildly sweet and reminiscent of its close cousin, cabbage. Kohlrabi can be eaten both raw and cooked and is chock full of fiber, potassium and vitamin C. The edible portion of kohlrabi is actually its swollen, fleshy, above-ground stem, despite the fact that it’s often called a bulb. Kohlrabi is delicious when sliced in salads, grated into slaws, prepared as breaded-and-fried cutlets and even tossed into stir-fries and soups.

There are two ways to grow kohlrabi. For an early spring harvest of this cool-season crop, start seeds indoors, under grow lights or in a bright window, about four to six weeks before our last expected spring frost. Seeds should be sown about a quarter-inch deep in a pot or nursery flat filled with sterile potting mix.

After the seedlings form their first true leaves, they can be separated and transplanted into cell-packs or small pots. These seedlings can then be transplanted outdoors into the garden as soon as the nighttime temperatures are consistently above 30 degrees. Space them 5 to 6 inches apart.

If you don’t have the time or inclination to start your kohlrabi seeds indoors, you also can grow this crop by directly seeding them into the garden.

As soon as the soil can be worked in the spring, usually in early to mid April, sow the seeds an inch apart at a depth of a quarter of an inch. Be sure to work an inch or two of finished compost into the planting area before sowing the seeds. You’ll need to thin the resulting seedlings to 4 inches apart when they reach about an inch tall. This will give the remaining seedlings plenty of room to grow.

Most kohlrabi varieties are harvested between 60 and 65 days after planting, although as soon as the “bulb” reaches the size of a tennis ball, it’s ready to be picked.

Because kohlrabi prefers cool weather, planting the seeds too late in the season results in a woody, dry harvest. But, it’s also possible to have a fall harvest of this crop. To grow late-season kohlrabi, sow more seeds into the garden in late July or early August. These will be ready to harvest in the autumn and early winter.

Some of my favorite kohlrabi selections include the red-skinned varieties ‘Delicacy Purple,’ ‘Blaril’ and ‘Azur Star,’ as well as the white-fleshed ‘Korridor’ and ‘Korist’ and the giant-type ‘Superschmelz.’

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is jessicawalliser.com.

Send your gardening or landscaping questions to [email protected] or The Good Earth, 503 Martindale St., Third Floor, Pittsburgh, PA 15212.

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    All About Growing Kohlrabi

    Storage kohlrabi varieties include’ Kossak’ (F1; 80 days),’Gigante’ (up to 130 days), and ‘Superschmelz’ (60 to 80 days). When given wide spacing and regular water, these storage varieties produce very large bulbs that are up to 10 inches across. The bulbs will store for weeks in a refrigerator or cold root cellar.

    For your first spring sowing of kohlrabi, start seeds indoors about six weeks before your last spring frost date. Kohlrabi is not as cold-tolerant as other cabbage family crops, so wait until two weeks before your last frost date to set out seedlings. This is also the best time to direct-sow seeds in a well-prepared bed.

    Kohlrabi plants are heavy feeders that demand moist, fertile soil with a pH between 6.0 and 7.5. Micronutrients are important, so take the time to amend the soil with compost and a standard application of a balanced organic fertilizer before planting. Thin or transplant seedlings to 8 inches apart, but allow more space when growing large, vigorous storage varieties. When growing kohlrabi in spring, use a biodegradable mulch of grass clippings or coarse compost to insulate the roots from summer’s heat.

    Start seeds of storage varieties in midsummer, at about the same time you would sow broccoli or cabbage for fall harvest. This is usually about 90 days before your average first fall frost date. Harden off the seedlings before setting them out in well-prepared soil, and plan to cover them with lightweight row cover or tulle to exclude insect pests.

    For recommended planting dates for your local climate — and to design your garden beds — try our Vegetable Garden Planner.

    In spring, you may need to protect kohlrabi from cold winds with cloches or a tunnel covered with row cover or perforated plastic. Featherweight row cover held aloft with hoops or stakes is the easiest way to protect actively growing kohlrabi from insects. Should the little plants refuse to grow even after the soil warms up in spring, drench them with a high-nitrogen fertilizer, such as fish emulsion, every two weeks.

    Harvesting and Storage

    Pull up entire plants when kohlrabi bulbs reach 3 inches in diameter. Cut off the roots and leaves and store the bulbs in your refrigerator. Kohlrabi will keep in the refrigerator for several weeks, or you can blanch and freeze uniform chunks of peeled kohlrabi.

    Some people enjoy eating the young leaves taken from the tops of kohlrabi as cooked greens, especially in fall when the leaves tend to be sweet and tender. This is seldom true of leaves taken from kohlrabi that has grown in warm weather.

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    Propagating Kohlrabi

    As biennials, kohlrabi plants produce yellow flowers followed by elongated seedpods in their second year. Seedlings that are exposed to more than two weeks of cold spring weather may bloom in their first year. After the flowers fade and the seedpods dry to tan, gather them in a paper bag, and allow them to dry indoors for a week. Shatter the dry pods and collect the largest seeds for replanting. Under good conditions, kohlrabi seeds will store for up to 4 years.

    For growing advice for many more garden crops, check out our complete Crops at a Glance Guide.

    Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on Google+.

    View full sizeKohlrabi ‘Green Queen,’ from New Dimension Seed, grows up to 3 pounds without getting pithy.

    Kohlrabi has been called the mongrel of the vegetable kingdom. The squat, awkward, alien-looking plant gets little honor, yet it is sweet, rich in nutrients and easy to grow, and it can be sown from seed twice a year, yielding both a spring and a fall crop.

    The stems, leaves and bulbs of this cabbage family member all can be eaten. The bulbs taste like nutty turnips and can be eaten raw or cooked. For best flavor, don’t peel the bulbs. The crispy, sweet young leaves and stems can be stir-fried or sliced raw.

    To grow kohlrabi (hardy to 10 degrees), start with a site in full sun with humusy, well-drained soil with a pH between 6 and 7. Apply 1 cup of balanced organic fertilizer per 10 feet of row at the bottom of a 3- to 4-inch-deep furrow. Cover with soil. Then sow kohlrabi seed about 1/2 inch deep and 1/2 inch apart in staggered rows.

    In the Willamette Valley, sow seed outdoors in late winter or early spring as soon as the soil can be worked. Sow again every two weeks through April. Planting later in spring produces harsh-tasting, fibrous bulbs. For a fall crop, sow seeds between July 20 and Aug. 10. Summer-sown seeds benefit from some shade.

    Plant seeds 1/2 inch deep and 1/2 inch apart in rows 15 to 18 inches apart. When seedlings are 4 to 5 inches tall, thin them to 5 inches apart.

    Every month, use a foliar seaweed drench for best production. The secret of good kohlrabi is fast growth. Slow-grown bulbs are pithy and fibrous. Keep soil moderately moist all the time. Mulches will help.

    After the late spring harvest, plant the bed with snap beans or other legumes to help enrich the soil.

    Underplant green kohlrabi with prostrate rosemary, nasturtiums or lettuce. Purple kohlrabi makes an nice skirt around purple perennials such as

    ‘Hidcote’ lavender and purple kale.

    To thwart diseases and pests, rotate beds, plant on time, keep plants well-fed and use row covers if conditions warrant. Surrounding seedlings with a cardboard collar helps prevent damage by cabbage root flies.

    Most kohlrabi varieties are ready for harvest when 1 to 1-1/2 inches in diameter, with an exception noted in the variety list. I like to harvest it young so it’s sweet. If the bulbs are not used right away, remove the outer leaves but leave those at the top to preserve freshness longer, and store in the refrigerator.

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    — Vern Nelson

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    Quick Guide to Growing Kohlrabi

    • For a spring harvest, plant kohlrabi 4 weeks before the last frost.
    • Space kohlrabi 9 to 12 inches apart in an area with plenty of sun and rich, well-drained soil with a pH of 6.5 to 6.8.
    • Improve native soil by mixing in several inches of aged compost or other rich organic matter.
    • Kohlrabi is a quick producer, so keep soil moist by giving plants 1 to 1.5 inches of water each week.
    • Encourage excellent leaf production by feeding plants regularly with a water-soluble plant food.
    • Block weeds and retain soil moisture by applying a thick layer of mulch made from organic material such as finely ground leaves or bark.
    • Harvest kohlrabi when leaves are 2.5 to 4 inches wide.

    Soil, Planting, and Care

    Set out spring plants about 4 weeks before the last frost so they mature in cool weather. Plants just out of a greenhouse need initial protection from freezes. Set out fall plants about 6 weeks before the first frost. In fall, plants “hardened” by gradual exposure to cool weather are tolerant of frost. Kohlrabi that matures in cool weather is deliciously sweet.

    Kohlrabi needs at least 6 hours of full sun each day; more is better. Give it fertile, well-drained, moist soil with plenty of rich organic matter. A soil pH between 6.5 and 6.8 discourages clubroot disease. To check pH, test the soil with a purchased kit, or get a soil test through your regional Cooperative Extension office. Fertilize and lime according to test recommendations.

    Without a soil test, add nitrogen-rich amendments such as blood meal, cottonseed meal, or composted manure to the soil, or amend the soil with a few inches of Miracle-Gro® Garden Soil for Vegetables & Herbs to provide nutrition, improve soil texture, and help protect against over- and under-watering. Space plants 9 to 12 inches apart. It’s also a good idea to feed kohlrabi plants regularly with a continuous-release vegetable fertilizer such as Miracle-Gro® Shake ‘n Feed® Tomato, Fruit & Vegetable Plant Food, following label directions.

    Kohlrabi needs an even supply of moisture to produce good bulbs. Mulch with compost, finely ground leaves, or finely ground bark to keep the soil cool and moist and to keep down weeds. Apply 1 to 1.5 inches of water per week if it doesn’t rain. You can measure the amount of water with a rain gauge.

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