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This odd looking vegetable came into my life about 10 years ago. And, from the start, I was hooked.
Kohlrabi was crisp and juicy, with a mild, pleasant flavor. Since that first bite, it’s become part of my regular diet.
Fun Fact: Kohlrabi is a German word kohl (meaning cabbage) and rabi (meaning turnip). Sometimes it’s referred to as a turnip cabbage or German turnip.
Its bulb looks like a cabbage and is shaped somewhat like a turnip.
However, though it’s shaped like a turnip, kohlrabi is not a root vegetable. Although sometimes it’s referred to as one.
A kohlrabi’s bulb is actually a thickening or swelling of the plant’s stem. This swelling forms just above the ground. The leaves then extend out from this swollen stem, giving kohlrabi its weird alien look.
Kohlrabi has more in common with the cabbage part of its name. And, just like cabbage, is a member of the Brassica family.
It can be purple or green in color.
Both are delicious and versatile and can be eaten raw or cooked. Personally, I love making Kohlrabi fries or having raw sliced kohlrabi in my salads.
Although the bulb is the most common part to eat, kohlrabi leaves are also edible. But, I find older, larger leaves can be tough.
In this guide, we’ll go over the ins and outs of growing kohlrabi. Soon, you too can start enjoying this delicious vegetable.
Contents
- Nutritional Information
- Common Kohlrabi Varieties
- Planting Your Kohlrabi
- Type of Soil
- Light Requirements
- Watering Your Kohlrabi
- Maintaining Your Kohlrabi
- Harvesting Your Kohlrabi
- Pests That Affect Kohlrabi
- Diseases That Affect Kohlrabi
- Kohlrabi Recipes
Beginner’s Guide to Growing Kohlrabi
Kohlrabi is a versatile vegetable that’s fairly easy to grow. But, there are a few things to keep in mind if you want your kohlrabi bulb to form properly.
In general, kohlrabi grows faster than other members of the Brassica family, though it’s not quite as hardy. Still, kohlrabi is well worth your effort.
1. Nutritional Information
Not only is Kohlrabi tasty, but it’s also good for you. Kohlrabi has approximately 36 calories in one cup. And, per the USDA, Kohlrabi contains the following nutrients.
- Protein 2.3 g
- Fiber 4.86 g
- Calcium 4 mg
- Magnesium 25.6 mg
- Phosphorus 62.1mg
- Potassium 472 mg
- Folate l21.6 µg
- Vitamin B-6 0.203 mg
- Vitamin C 83.7 mg
2. Common Kohlrabi Varieties
There are over 22 varieties of kohlrabi. Here are a few common ones.
Early White Vienna – light green in color with a smooth round bulb. The flesh is creamy and tender with a mild flavor.
Konan Hybrid – has a smooth globe shape that’s pale green in color. The flesh is crunchy and sweet. The bulb can grow to 6 inches in diameter without losing its flavor. This variety is also pest resistant and produces early.
Kossak – this variety takes a little longer to mature, but it’ll grow up to 8 inches in diameter and still maintain its shape and flavor. It also stores well, even up to 4 months, as long as you keep it cold after it’s harvested.
Azur Star – the skin of this kohlrabi is purple, but the inside is white and crisp. An Azur Star has a flattened round shape and a diameter slightly smaller in size. It should be harvested when it reaches 2 to 3 inches.
Gigante – takes longer to mature, up to 130 days. But it’s a whopper, growing to 10 inches in diameter without becoming woody. The skin is pale green and the flesh is white and crisp with a mild, tangy flavor.
The above is just a sampling of kohlrabi varieties. If you’d like to know of other types, take a look at this list from the Gardeners Path.
3. Planting Your Kohlrabi
Kohlrabi prefers cool weather. It can be planted as a spring or fall crop.
Don’t plant your kohlrabi where, in the previous few years, you’ve planted relatives of kohlrabi.
When the same family of crops is planted in the same spot each year, eventually they deplete the soil of the nutrients they need. This is especially true if you’re not amending the soil. Also, if there’s been a disease, that disease can linger and spread to the current batch of crops.
So it’s important you rotate where you plant your crops every few years. And it’s no different with Kohlrabi.
Kohlrabi seeds can either be started indoors or sown directly into the ground.
Starting Seeds Indoors
Start kohlrabi seeds indoors roughly 4 – 6 weeks before you expect the last spring frost.
Kohlrabi seeds don’t need a heating mat, or anything special. A cool room with a bright overhead light will do.
Once the threat of frost passes, transplant your seedlings to your garden. It’s important you harden off your plants first. In other words, get them used to the outdoors before putting them outside permanently.
If you’re buying seedlings from a nursery, make sure those seedlings are healthy. The leaves should be green, without signs of yellowing. And the plant should not be overgrown.
Starting Seeds in the Garden
When sowing your plants directly into the ground, sow the seeds ¼ – ½ inch deep about 2 inches apart.
Once the seedlings sprout, thin your plants to at least 4 – 6 inches apart. The further apart the better. And, if you’re growing a larger variety, make sure to check the package directions. Thin these enough to accommodate the larger size.
Planting Kohlrabi in the Spring
In general, spring kohlrabi is planted mid-April through May, once the soil temperature reaches 45℉ and after the last spring frost.
With a spring crop, choose a smaller-sized variety that matures fairly quickly. Kohlrabi doesn’t like hot weather. So, you want your kohlrabi ready for harvest before temperatures reach 75℉ or higher.
Planting Kohlrabi in the Fall
For a fall crop, kohlrabi can be planted anywhere between midsummer through fall, depending on your hardiness zone.
You’ll generally want to sow your seeds at least six weeks before the first fall frost.
Larger kohlrabi varieties are good ones to plant for a fall crop. They can stay in the ground longer without losing their flavor. Remember these varieties can take longer to mature, so plant according to their time frame.
In warmer, southern regions, kohlrabi can be grown throughout the winter.
Growing Kohlrabi in Containers
Kohlrabi also makes a great vegetable for a container garden. But you do need to use a large enough planter.
Though it has a shallower root system, a kohlrabi plant can spread outwards and upwards anywhere from 16 to 24 inches. So, your pot should be at least 16 inches wide and 12 – 16 inches deep. This size will hold 3 to 4 smaller-sized varieties.
As with inground planting, once your Kohlrabi seedlings are a couple of inches high, thin your plants until they’re at least 4 – 6 inches apart.
4. Type of Soil
Kohlrabi likes loamy, well-draining soil best. The soil needs to stay moist but not become overwatered or waterlogged.
If you’re planting in sandy soil, plan on watering more frequently. Clay or heavy soil, on the other hand, will likely need water less often.
The pH balance of the soil should be anywhere between 6 to 7.5. Kohlrabi prefers slightly acidic soil. If you’re not sure of your soil’s acidity you can use a pH tester.
For other gardening tool suggestions, check out my post on garden tool essentials.
You can add compost or manure to the soil to help nourish your kohlrabi. But, make sure it’s aged, as fresh manure can harbor disease. Grass clippings and mulch are other great soil additives.
With a container, the soil depth should be at least 12 inches.
Use a quality potting mix that is both rich, and well-draining. I wrote an article on bagged soils and mixes. You’ll find it helpful when it’s time to choose your soil.
I don’t recommend using garden soil or heavy compost in containers. These types of mediums can be too dense for a pot, which can lead to your pot retaining too much water.
5. Light Requirements
Kohlrabi needs 6 or more hours of sunlight per day.
But, although it likes lots of sun, kohlrabi doesn’t like hot temperatures. Ideally, grow this cool weather crop in temperatures between 40℉ to 75℉.
Higher temperatures can stress the plant, affecting bulb growth and resulting in tall, weak plants.
Temperature fluctuations can also spell trouble. For example, a cold snap followed by temperatures rapidly warming may cause your Kohlrabi to bolt. In other words, it’ll go to seed.
Kohlrabi can take a mild to moderate frost. But, consistent temperatures below 45℉ can also cause your plants to flower.
6. Watering Your Kohlrabi
While your kohlrabi seeds are germinating, it’s important the soil is kept moist.
And kohlrabi plants need consistent water throughout the growing season in order for their bulbs to form properly.
On average, Kohlrabi needs 1 – 1½ inches of water per week. Whether that water comes from you or from the sky.
Overheated plants may have a hard time absorbing water. They can crack and become fibrous and bitter tasting.
The best Kohlrabi grows fast without any heat or moisture stress.
7. Maintaining Your Kohlrabi
Kohlrabi starts out with a thin stem that supports several leaves. In roughly 25 to 30 days, that stem starts to swell just above the soil.
And this is where the bulb forms.
There’s usually one bulb per plant and multiple leaf stems will extend from that bulb. This gives kohlrabi its weird, alien-looking appearance.
There’s no need to prune the leaves. Although the bulb is the main part you eat, the leaves are also edible.
Kohlrabi plants generally grow to heights of 16 – 24 inches. Their bulbs can be anywhere from 2 – 12 inches in diameter, depending on the variety and when they mature.
Maintenance
The two most important maintenance tasks are thinning your kohlrabi seedlings and keeping your plants evenly moist throughout the growing season.
Smaller varieties should be thinned until there are at least 4 – 6 inches of space in between each plant. The more space, the better.
Larger varieties might need up to 12 inches of space between each plant. The directions on the seed packet should tell you the recommended distance.
It’s a good idea to mulch around the plants using compost, bark, or ground-up leaves. This helps retain moisture and keep the bulbs cooler. Which is especially important if the humidity level is low.
Fertilizer
If you started with rich soil, and have occasionally side-dressed it with mulch or aged compost then fertilizing is not a necessity.
However, if you want to give your plant an extra boost, or your soil is only so-so, then use a nitrogen-based fertilizer. This means the fertilizer has more nitrogen than other nutrients.
Nitrogen is the first number on a fertilizer label. This number should be greater than the other two. For example, the label might read 10-5-5.
Kohlrabi grown in containers will likely need fertilizing as the nutrients may be depleted through watering.
Whether inground or in a container, make sure you fertilize around the outside of the plant and not directly on the bulb.
8. Harvesting Your Kohlrabi
In general, it takes 50 – 70 days for Kohlrabi to mature.
Most varieties call for harvesting when the bulb reaches 2 – 4 inches in size. But, this depends on the type you’ve planted.
Larger varieties can grow anywhere from 6 inches to even 10 inches before needing picking.
In spring, harvest your kohlrabi before the weather gets too hot (75℉ or more). If you wait too long to harvest your kohlrabi, it can become woody and fibrous.
Kohlrabi can tolerate mild to moderately heavy frost. And, in fact, a light frost can enhance the flavor. However, it can’t take consistent cold temperatures.
In the fall, plan to harvest your kohlrabi within 1 to 2 weeks of your first winter frost.
I’ve written an article on kohlrabi and winter. You’ll find it helpful when it comes to fall plantings.
How to Harvest Your Kohlrabi
If harvesting your kohlrabi in stages, pick every second one. This will give the others more room to grow. Which is especially important if you’ve planted a giant variety.
Kohlrabi can either be pulled from the ground, root and all, or the root can be cut off at ground level and then left in the ground.
Kohlrabi leaves are edible, so there’s no need to throw them away.
How to Store Your Kohlrabi
After picking, store your kohlrabi in a cool, moist environment. How long it lasts depends on the variety and how well you’re able to maintain that cool environment. Sometimes, that can be difficult in a home setting.
In the fridge, Kohlrabi can last up to 4 weeks.
Before storing, remove the leaves and wash your kohlrabi.
Although the skin on kohlrabi is edible, it can be tough. Especially thicker skin. Most people, myself included, peel Kohlrabi before eating it. You can peel your Kohlrabi with a vegetable peeler.
9. Pests That Affect Kohlrabi
Pests that affect kohlrabi can include,
10. Diseases That Affect Kohlrabi
Diseases that affect kohlrabi can include,
11. Kohlrabi Recipes
Kohlrabi is a delicious, versatile vegetable. Here are just a few ways to make use of this tasty edible.
Final Thoughts
- Kohlrabi can be planted as a spring or fall crop.
- Thin kohlrabi plants to at least 4 – 6 inches apart. Distance may be greater depending on the variety.
- Kohlrabi needs at least 6 hours of sunlight each day and needs even moisture during the growing season.
- In spring, kohlrabi should be harvested before temperatures reach 75℉ or higher.
- In the fall, kohlrabi should be harvested within one to two weeks after the first frost.
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