- How To Grow Kohlrabi – Growing Kohlrabi In Your Garden
- How to Grow Kohlrabi
- How Does Kohlrabi Grow?
- How to Plant Kohlrabi
- When to Harvest Kohlrabi
- Your comments and tips
- How to Grow Kohlrabi
- Planting Kohlrabi: All in the Timing
- A Three (Or Four) Season Kohlrabi Harvest
- Kohlrabi Growing Rules
- Growing Kohlrabi: Small is Beautiful
- Kohlrabi Selections and Suppliers
- Veggie Varieties
- Proper Planting Tips
- The Right Size for Picking?
- HOW TO GROW KOHLRABI
- TYPES OF KOHLRABI
- QUICK CALENDAR FOR GROWING KOHLRABI IN THE AVERAGE UK AREA
- WHERE TO GROW KOHLRABI
- SOWING KOHLRABI SEED INSIDE
- SOWING KOHLRABI SEED OUTSIDE
- CARE OF KOHLRABI
- WHEN AND HOW TO HARVEST KOHLRABI
- SAVING SEED FROM KOHLRABI IN THE UK
- TOP PERFORMING VARIETIES OF KOHLRABI
- KOHLRABI PEST AND DISEASE
- CABBAGE WHITE BUTTERFLY
- Planting Kohlrabi
- Caring for Kohlrabi
- Harvesting and Storing Kohlrabi
- Kohlrabi Varieties to Grow
- Harvesting Kohlrabi Plants: How And When To Pick Kohlrabi
- Kohlrabi History and Appearance
- Growing Kohlrabi
- How Long to Wait for Kohlrabi Harvest
- How to Harvest Kohlrabi
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.
Your comments and tips
Post a comment or question Display Newest first | Oldest first, Show comments for Australia | for all countries 17 Jan 20, Carol (New Zealand – sub-tropical climate) When is best time to grow kohlrabi in Auckland? 10 Nov 19, Duana (Australia – temperate climate) Hi, my kohl rabi have failed to form the swollen tuber. They are 30cm tall and long stems, have been in the ground for 10 weeks, planted out from seedlings I raised myself and look really healthy. In raised garden bed, full sun, new soil and surrounded by successful snow peas, lettuce, broad beans and radish crops. What have I done wrong ? 06 Oct 19, Viv Forbes (Australia – temperate climate) where can we buy vegie seeds on internet? 08 Oct 19, anon (Australia – sub-tropical climate) Try on-line seed selling companies, 03 Jul 19, Josephine (Australia – sub-tropical climate) Live in Hervey Bay qld growing kohl rabi was wondering what pest would bite big chunks out of bulb not eating leaves 04 Jul 19, Janette (Australia – sub-tropical climate) Could be one of our natives such as Bandicoot which dig down to eat roots of plants. 04 Jul 19, (Australia – temperate climate) Some kind of grub in the soil ??????? 21 May 18, Kat (Australia – temperate climate) HI, I am trying to grow Kohlrabi for the fist time. We live in Newcastle, north of Sydney. I planted the seeds at least a month ago. Lots of leaves but no swelling at the base yet. I was wondering how long it takes to form? 23 May 18, Mike (Australia – temperate climate) It says 7-10 weeks – give it some time if it is only 1 mth old. 23 May 18, Kat (Australia – temperate climate) Thanks. I have read elsewhere that it may be too warm here to grow it successfully. I hope not tho as my son has been eagerly looking forward to seeing this rather unusual veggie growing. 🙂 Showing 1 – 10 of 63 comments
How to Grow Kohlrabi
Planting Kohlrabi: All in the Timing
Like other members of the cabbage clan, kohlrabi thrives in cool temperatures.
“You can grow kohlrabi in almost any region if you grow it in the spring or fall,” says Stephen Reiners, associate professor of horticulture for Cornell’s New York State Agricultural Experiment Station. “Good timing is key. You want to avoid having the bulbs form in hot weather, which can make them woody.” Allow 50 to 65 days from the time you sow your kohlrabi seeds to harvest, advises Reiners.
Brian Luton favors fall for growing kohlrabi at Stone’s Throw Farm in Nedrow, N.Y. From mid-July through early August, Luton starts the seeds in a greenhouse, using a homemade mixture of peat, perlite and vermiculite amended with greensand (glauconite), rock phosphate and lime, as well as 15 percent to 20 percent finished compost. “Kohlrabi likes a decent amount of compost right out of the gate,” he notes.
Luton transplants the small seedlings to the garden two to three weeks later (usually by the end of August), planting them 8 inches apart, with 10 to 12 inches between rows. The bulbs are ready for harvest by mid-September through October, depending on the variety and seasonal conditions, but they also can stay in the ground for on-demand harvests. “The mature bulbs are very frost tolerant and hold well in the garden,” he says. “In mild winters, I’ve harvested them in January.”
Growing kohlrabi for fall harvest has another advantage: “A light frost will actually enhance the bulbs’ flavor, making them sweeter, the same way it does with other cabbage family crops,” Reiners says.
For a spring crop, beat the heat by starting your seeds indoors about six weeks before your last expected frost. You can sow kohlrabi seeds directly in the garden, but you’ll have a better chance of avoiding the heat by starting the seeds earlier, indoors.
At Harmony Valley Farm in Viroqua, Wis., Richard de Wilde and his crew get an extra-early start by sowing kohlrabi seeds in the greenhouse in early March, eight to 10 weeks before their last frost date. He transplants the seedlings into raised garden beds in mid-April.
“We keep them under a row cover until daytime temperatures reach about 75 degrees,” explains de Wilde. “Kohlrabi tolerates cold temperatures, but the row cover provides enough extra warmth to keep the plants growing strong and fast. It also shields them from flea beetles, the only threat we’ve seen at this time of year.”
De Wilde harvests early kohlrabi varieties, such as ‘Kolibri,’ several weeks before broccoli and most other spring vegetables are available. “Our customers really look forward to it.”
A Three (Or Four) Season Kohlrabi Harvest
In regions with the mildest winters, kohlrabi will prosper from fall through spring. Tucker Taylor, manager of Woodland Gardens in Winterville, Ga., grows a number of crops year-round for Atlanta-area chefs and farmers markets, but kohlrabi is a cool-season standard.
“We like it because it’s so quick,” he says. “We rotate it through our hoop houses from fall through spring, and harvest the bulbs at different stages.” Taylor’s crew first starts the seeds in a greenhouse using Sunshine Mix, an organic seed-starting medium. “We add a little kelp to the mix to provide micronutrients,” he says. The seedlings are then transplanted into the hoop houses about a month later; full-size bulbs are harvested about six weeks after that.
Taylor also grows baby ‘Purple’ kohlrabi greens year-round in a greenhouse, which is heated only enough to keep the tender greens from freezing on extra-cold nights.
“The kohlrabi serves as the base of our microgreens mix, which also includes red mustard, broccoli, ‘Red Russian’ kale, red amaranth and arugula,” he explains. “It adds bright color to the mix and is very easy to grow.”
For his savory mix, Taylor grows the various greens individually in open flats filled with earthworm castings. When the greens are about 10 to 12 days old, he snips the leaves with scissors just above soil level, blends them together, and bags them for sale.
Kohlrabi Growing Rules
Beyond the need for cool temperatures and full sun, kohlrabi is not especially demanding. “Anything you can do to ensure steady, consistent growth will help,” Reiners says. “Too much stress on the plant — such as drought or high temperatures — can affect the bulb, causing it to become woody or spicy like a radish. With even temperatures and consistent soil moisture, kohlrabi will stay tender and mild.”
The best way to provide those stress-free conditions is to be sure your soil contains plenty of organic matter (such as compost, grass clippings or well-rotted manure) that releases nutrients and moisture slowly and steadily.
Kohlrabi is not a heavy feeder. A generous layer of clippings or compost (half inch to 1 inch) worked into the soil before planting should provide all the needed nutrients. For an extra boost, side dress the plants with a little more compost when you first notice the bulbs beginning to swell.
A layer of organic mulch (such as straw or shredded leaves) will also help moderate soil temperature and moisture. But for spring kohlrabi crops, only add the mulch after the soil has warmed. Otherwise you risk slowing your plants’ growth.
Insect pests and diseases shouldn’t be a problem. “We do use insect screens on the sides of the hoop houses, but we haven’t found cabbage loopers to be a problem the way they can be on other cabbage crops,” Taylor says. If the small green worms known as cabbage loopers do show up, simply use Bt (Bacillus thuringiensis) to keep them in check.
Growing Kohlrabi: Small is Beautiful
Kohlrabi won’t keep you waiting long. Within weeks of planting, you’ll see the stems begin to swell and form the funny round globes that prompted its nickname, “space cabbage.” Soon after that, your kohlrabi will be ready to harvest.
If it’s spring, don’t hesitate: Kohlrabi is most tender and mild-flavored when the bulbs are no more than 2 to 3 inches across, Reiners says. Fall-grown kohlrabi is less touchy. In fact, the plants will tolerate temperatures to 10 degrees, so you can harvest at a more leisurely pace.
You’re bound to cook up plenty of ways to enjoy your harvest. Both the bulbs and leaves are extremely versatile. But if you find you just cannot use all your kohlrabi at harvest time, it’s no big deal. Simply trim off the leaves and stems, wrap the bulbs in plastic and store them in your refrigerator or a root cellar for several months. Pretty cool, huh?
Kohlrabi Selections and Suppliers
Seasoned kohlrabi growers recommend the following varieties. The numbers after each description refer to the suppliers listed below.
• ‘Kolibri’: (Hybrid) 45 days; purple-veined leaves; fiberless white flesh (2, 3)
• ‘Early Purple Vienna’: (OP) 55 days; slower growth means less cracking in wet weather (4)
• ‘Korridor’: (Hybrid) 50 days; white bulbs with dark green leaves; holds its quality longer than most (1)
• ‘Early White Vienna’: (OP) 55 days; sweet and mild; slower growth means less cracking (4)
• ‘Superschmelz’: (OP) 60 days; bulbs grow up to 8 to 10 inches without becoming woody; deep roots a plus in dry climates; best for fall harvest and storage (3)
• ‘Purple’: (OP) 10 to 12 days for young seedlings; leaves and stems can be used with other young greens for microgreens mix (2)
• High Mowing Organic Seeds, Wolcott, Vt., (802) 472-6174
• Johnny’s Selected Seeds, Winslow, Maine, (877) 564-6697
• Territorial Seed Co., Cottage Grove, Ore., (800) 626-0866
• Victory Seeds, Molalla, Ore., (503) 829-3126
Vicki Mattern is a contributing editor for MOTHER EARTH NEWS magazine, book editor and freelance magazine writer. She has edited or co-authored seven books on gardening, and lives and works from her home in northwestern Montana. You can find Vicki on Google+.
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.
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:
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.
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.
Photo credit: , unless otherwise noted.
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 an often-ignored crop in home vegetable gardens, and we think that’s a shame. It’s easy to grow and surprisingly tasty. The roots are high in vitamin C, and the leafy greens are a great source of vitamin A, folate, and calcium. It grows quickly and prefers cooler weather, making it a great crop for a fall garden.
Kohlrabi is very similar in growth habit to turnips and rutabagas, but it is grown for its swollen stem instead of its root structure. When mature, it appears as roundish bulbs sitting on the surface of the soil.
Harvest when bulbs are 2-3 inches in diameter. You can harvest up to ⅓ of the leaves off of each plant while the bulb is still growing.
Growing Kohlrabi: Plants should be spaced 4-6 inches apart, in rows 12 inches apart. If direct-seeded, the plants must be thinned to these specifications. Transplant or direct-seed into loosened, moist, fertilized soil. Plants need consistent water to grow, so if the fall rain has not come yet, water regularly after planting.
Kohlrabi greens can be used much like kale or collards. The smallest leaves are tender enough to put in salads or on sandwiches, but the larger, more mature leaves will be thick and tough without cooking.
Recommended variety: Kolibri
Add a little color to your fall garden with this vibrant purple variety. It matures from seed in 45 days, and if transplanted into the garden it can be ready to harvest in 30 days!
Thinking about planting kohlrabi, but don’t know how you would cook with it? Our friends at the kitchen have you covered!
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.
HOW TO GROW KOHLRABI
TYPES OF KOHLRABI
There are two common types of Kohlrabi, those sown in spring which tend to be green and those sown in summer / autumn which tend to be purple. The purple types are hardier and can often be left in the ground up till December time especially if you can provide cloche protection or grow them in polytunnels / greenhouses.
QUICK CALENDAR FOR GROWING KOHLRABI IN THE AVERAGE UK AREA
Before using the calendar below, why not adjust it to your weather conditions?
Not only will the calendar below be correct for your area but all dates in this site will also be adjusted. Your setting will last for six months or more and still be set when you revisit this site. If you prefer not to adjust the dates they will be the average for the UK.
Spring sowing indoors – March week 3
Spring sowing outside – April week 1
Harden off – April week 3
Plant out spring sowing – April week 4
Sow for autumn crop – July week 4
WHERE TO GROW KOHLRABI
Kohlrabi grow in most soil types but they perform best in the following conditions:
- A well-drained soil which has been well dug to include lots of well-rotted organic material.
- Do not add manure to the site before sowing seed.
- Kohlrabi prefer a neutral to slightly alkaline soil. They don’t do well on acid soils. See here for more about soil acidity / alkalinity.
- They grow equally well in full sun and partial shade. They don’t like dry soil however so if that might be a problem on your plot, position them in partial shade where the soil will remain moist for longer.
SOWING KOHLRABI SEED INSIDE
This is the easiest method for a spring sowing although for an autumn crop the seed should be sown directly outside as described in the next section.
Plastic seedling modules available from garden centres and online are ideal, each module is about 5cm square. Sow the seeds as follows:
- Over fill the seed module tray with good quality multi-purpose compost which has had all the lumps removed.
- Firmly tap the filled tray on a solid surface a couple of times to settle the compost but don’t firm it down. Scrape away the excess compost from the surface so that the compost is level with the top of the modules.
- Use a pencil or a your little finger to make a hole in the compost of each module about 2cm deep.
- Drop one seed into each hole and sprinkle in a little compost over the seed so that the compost is again level with the top of the module.
- Water the compost and place a marker in one module showing the sowing date and variety name.
- Place the seeds on a windowsill or any light and airy position where the temperature is in the range 50°F / 10°C to 80°F / 27°C, room temperature is ideal. Kohlrabi seeds will germinate in temperatures as low as 40°F / 4.5°C.
The seeds will germinate in about 10 days and be ready for planting outside in four weeks from the date the seeds were sown. They don’t need to be potted up or fed, they will grown fine in the modules until planting out.
HARDEN OFF KOHLRABI SEEDLINGS
The plants will be ready for hardening off about four weeks after sowing seed. Hardening off is simply the process of gradually acclimatising the plants to outside conditions and should take a week or so. More detailed information about hardening off plants can be found here. The plants will be about 8cm high when they are ready for planting out.
PLANTING OUT KOHLRABI
If you have prepared the soil (i.e. well dug) as described above, planting the seedlings out is simple. First work into the top of the soil a handful of blood, fish and bone per square metre. Tip the plant out of the module and plant it in the ground gently firming the soil around it. Each plant should be 30cm / 1ft apart and if planting more than one row, the rows should be 25cm / 10in apart.
It’s important to get the planting depth correct with Kohlrabi. They need to be planted to the same depth in the ground as they were in the compost of the module. This is particularly important because the edible part of kohlrabi is the stem just above soil level which swells into a small ball shape. If the stem where the ball forms is partially or fully below soil level it will rot.
Plant as described above and then water the them in well.
SOWING KOHLRABI SEED OUTSIDE
Kohlrabi can be sown outside either for an early summer or autumn crop, see the calendar above for precise dates. Kohlrabi has an excellent germination rate even in cold conditions so there is no need to sow the seeds densely. Before sowing prepare the soil by digging to a fine tilth and add one handful of blood, fish and bone per square metre.
Make a groove in the soil about 1 to 2cm deep and sow one seed every 5cm / 2in. Cover with soil and water well. If planting more than one row, the rows should be 25cm / 10in apart. The seedlings will appear in about ten days time and should be thinned to 30cm / 1ft apart.
CARE OF KOHLRABI
Kohlrabi are not demanding plants as far as care is concerned. The following should keep them more than happy:
- You could spread a handful or so of blood, fish and bone per square metre around your plants once a month but in truth they should be OK on any reasonable soil.
- Do water the plants in dry weather conditions because lack of water will lead to woody stems. They need more water compared to most other plants.
- To help with water retention a mulch around them will do wonders. Grass cuttings are an ideal and cheap solution which will also slowly rot down and provide a small amount of nitrogen feed.
WHEN AND HOW TO HARVEST KOHLRABI
Read the seed packet to work out how long your variety will take to mature but in general they take fifteen weeks or so from seed sowing to maturity. One plant will give you one Kohlrabi.
In theory you can leave the stems until they are 15cm or so wide and they should still be tender and very edible. But to do that you will need to have maintained a very even and constant moisture level in the soil. It’s probably best to harvest them when they are 5cm to 8cm wide (about the size of a tennis ball) if the growing conditions are not perfect.
To harvest, grip the swollen stem and gently tease the roots from the ground. Try not to disturb the plants growing at either side.
To prepare Kohlrabi for eating fresh or steaming cut the leaves off. The leaves are an edible green and should be treated as if they were kale. Cut the top and bottom stems off just slightly into the main swollen stem. Peel off the outer skin, larger stems will have thicker skins compared to smaller and more tender stems.
The Kohlrabi is now ready for eating. They are best eaten within 24 hours to maintain the tenderness but will store for four of five days in the fridge.
SAVING SEED FROM KOHLRABI IN THE UK
Kohlrabi is a biennial plant which means it grows in year one but only produces seed in the second year. So, in order to get the seed you will need to overwinter the plant. Most areas of the UK are too cold for the plant to survive through winter although in warmer areas it may be possible.
If the plant survives winter it will start to produce yellow flowers in May time on the ends of large stalks. The flowers will then die down and long thin seed pods will begin to form. At this point the plant will have grown to about 1.5m high and this is another problem. April / May winds in the UK can damage the plants significantly so the overwintered plants need to be a protected position.
The green seed pods will turn brown in June or July and the seeds can then be harvested. One plant will produce hundreds of seeds. Only open pollinated Kohlrabi is worth it for saving seeds, the quality of seed from F1 plants will be very variable.
Given the problems of overwintering, wind damage in spring and the space occupied by the plants when fully grown it’s only the most determined who will try saving Kohlrabi seeds for themselves in the UK! After all, a packet of shop bought seeds can cost less than £2.
TOP PERFORMING VARIETIES OF KOHLRABI
AZUR / AZUR STAR
Sometimes simply called Azur but the full name is really Azur Star. This is a purple skinned variety which is slightly unusual because it produces an excellent early summer crop. Many of the purple varieties are best reserved for an autumn crop.
It is bolt resistant but it’s still important to keep the soil evenly moist throughout the growing season to avoid the stems turning woody. Be wary of the seed company claims that it will survive drought. It will but the stems won’t taste good!
Azur Star grows well both outside or in a polytunnel / greenhouse. It can be sown for a summer or autumn crop. Autumn sown crops of Azur Star are not as hardy as some other purple varieties but should last in the ground until late October in most areas of the UK.
Recommended by Bob Flowerdew, this variety will grow to an enormous size if not harvested early. A 4kg stem is a real possibility. They don’t taste quite as good as some but even at their full size they are perfectly edible. They store (keep cool and moist) for a month or more.
Grow this variety for novelty value rather than it’s eating quality. If you think about it for a minute, a 4kg Kohlrabi is an awful lot to eat over a couple of days! Yes they store well but the minute you start peeling the skin the whole stem needs to be eaten within a few days.
This is a green skinned variety which should be sown in spring (see calendar above) and can be harvested any time from June onwards depending on how large you want it to grow.
An excellent green skinned variety which is best sown in spring. The flesh is more succulent than most and this variety matures quickly.
For an early crop grow under cloches, polytunnel or greenhouse and sow a couple of weeks earlier than mentioned in our calendar above. As an experiment try planting this variety just 5cm apart and harvest as baby kohlrabi, we did this last year and were impressed with the results.
KOHLRABI PEST AND DISEASE
All the normal pests and diseases which attack cabbages, Brussels Sprouts and other brassicas can attack Kohlrabi but out of all the members of this plant family they are probably the least affected. The most common problem is listed below.
CABBAGE WHITE BUTTERFLY
SYMPTOMS: Holes in leaves, generally poor plant health, the presence of caterpillars similar to those shown below or pale green coloured. The caterpillars will be most commonly seen in May and then June to August.
TREATMENT: For complete details on how to treat the Cabbage White Butterfly .
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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.
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
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.
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.
This close relative of the cabbage was bred over centuries to develop a flattened meristem. Sometimes referred to as German turnips, kohlrabis are very rich in vitamin C, and a great source of potassium. The flavour is like a very mild cabbage and the texture is crisp and crunchy, a bit like that of a pear. Great in salads or eaten raw. Follow along with this handy How to Grow Kohlrabi Guide and grow food.
Brassica oleracea var. gongylodes
We Recommend: Kolibri (KH434). We don’t recommend this wonderful hybrid kohlrabi for any other reason than how splendid looking it is in the garden. Kolibri has the same fine flavour and texture as Kongo, but hey – it’s bright purple! More gardeners need to grow familiar with this nutritious, easy-to-grow vegetable.
Season & Zone
Season: Cool season
Direct sow early April until mid-May for a crop to mature in about 8 weeks. Sow again mid-July to early August for fall and winter crops. Planting between mid-May and mid-July causes them to mature in hot weather resulting in inferior bulbs. Optimal soil temperature for germination: 10-30°C (50-85°F). Seeds should germinate in 7-10 days.
Sow seeds 5mm (¼”) deep with plants spaced 10-15cm (4-6″) apart in rows 30-45cm (12-18″) apart.
Ideal pH: 6.0-6.8. Kohlrabi is a moderate to heavy feeder that does best in humus-rich soil amended with composted manure. Mix ¼-½ cup complete organic fertilizer into the soil under each plant.
Spring-sown kohlrabi will get larger than tennis balls in fair soil, but if you pick them when they are still less than 5-8cm (2-3″) in diameter they will be sweet and tender. Fall-grown kohlrabi can grow larger yet stay tender. Kohlrabi is frost-hardy, and may last well beyond Christmas in the garden.
In optimal conditions, at least 80% of the seeds will germinate. Usual seed life: 3 years. Per 100′ row: 360 seeds, per acre: 104M seeds.
Diseases & Pests
Protect from cabbage moths and other insect pests with floating row cover. Prevent disease with a strict 4-year crop rotation, avoiding planting Brassicas in the same spot more than once every four years.
A worthy companion for beets, Brassicas, cucumbers, and onions. Avoid planting near peppers, pole beans, strawberries, and tomatoes.
More on Companion Planting.