Kohlrabi might be a vegetable you’ve never heard of if you live in a warmer climate or have a long growing season. If you are in a colder climate and have a shorter season, or you’re thinking of moving to one, then it’s an absolute must in your homestead garden.
This beautiful and tasty treat can be white, pale green, or purple. The swollen part of the stem is the part most commonly eaten, although the leaves are also edible and can be cooked in the same way one would cook kale or collards.
In the German language, kohlrabi translates to “cabbage turnip,” and as the name implies is part of the cabbage family. Relatives to the kohlrabi include arugula, broccoli, broccoli raab, Brussel sprouts, cauliflower, collards, kale, horseradish, mustard, radishes, and turnips.
It is a very hardy biennial crop that is grown mostly as an annual.
Picking A Good Kohlrabi Variety
The most common varieties are:
- Early White Vienna: a 55 day variety that is white (can be light green)
- Early Purple Vienna: a 60 day variety that is a radiant purple
- Grand Duke: a 45 day all American selection that is green
I grow the standard White Vienna and Purple Vienna.
Preparing The Soil For Kohlrabi
Choose a spot in your garden that receives full sun and drains well. Soil pH should be between 6.5-7.5.
Kohlrabi can be grown in average soil. However, the taste is significantly affected when it is allowed to grow in soil high in organic matter.
For better tasting stems, spread 1-2 inches of compost over your kohlrabi bed and work in thoroughly before planting your kohlrabi. Your efforts to provide fertile soil along with planting at the right time and harvesting promptly will lead to a mild and sweet flavor.
How To Grow Kohlrabi From Seed
Seeds can be sown directly in the ground (or indoors) 4-6 weeks before your last expected spring frost. I have in the past found sources that state starting 8 weeks before the last expected spring frost, but I urge you to try this with caution if you are in a colder area. In general, when you can begin working the ground, start thinking about starting your kohlrabi. Keep good notes in your garden journal (free downloads here), and you’ll find a schedule that works best for you.
Place seeds ¼ – ½” deep depending on your variety. Seeds should be 8 inches apart in rows 18-24″ apart, and soil should be kept evenly moist. As plants become large enough, apply mulch to protect them and keep from drying out.
If direct sowing into your garden and you have mild summers, you may find succession planting beneficial. Stop sowing seeds 8-10 weeks before the first fall frost.
Warmer climates (zone 9 & 10) will find succession planting through the fall yield winter & early spring harvest. Summer heat will turn leaves bitter.
Areas with cold winters generally do best planting in the early spring. The goal should be to have much of the growth done before hot weather hits.
Transplanting Kohlrabi Plants
If starting seeds indoors or purchasing them, remember to harden them off before transplanting them to your garden. Transplant when around 4″ tall, and water well with a nutrient rich tea when the plant is about one month old (not in the garden for one month).
Advanced Kohlrabi Planting
Once you’ve mastered rotation and timing in your garden, try tucking kohlrabi transplants between widely spaced fall broccoli (wider than normally spaced broccoli). Your kohlrabi will help shade your broccoli and deter weeds with it’s larger leaves and will be ready to harvest before broccoli gets big.
Short on space? Stagger rows of kohlrabi 6 inches apart, so that they are not in a grid pattern. Leaves of the kohlrabi in the next row over will fall between kohlrabi in the first row. Shading the root stalk will lead to more tender bulbs.
Growing Kohlrabi In A Container
I have read studies both ways that state that kohlrabi can and also shouldn’t be grown in containers. I have tried it myself without much success, although I do finally have one that looks promising.
My advice would be if your heart is set on trying it, then go for it–but don’t ever expect it to work. And certainly don’t think that you are a horrible gardener if you can’t get it to work.
Taking Care Of Your Kohlrabi Plants
The most crucial thing you must do to keep kohlrabi happy is to keep it watered. Make sure it is not allowed to dry out, but don’t drown it. Keeping it moist will keep the taste from becoming woody.
When you time your plantings, remember that although kohlrabi will tolerate some warmth, it is truely a cool weather plant. Time your plantings so that it will mature during cool weather.
Don’t allow your kohlrabi plant to get too big, or you may find it completely unpalatable.
When And How To Harvest Your Kohlrabi
Kohlrabi should be harvested when it’s bulb is 2 inches across (and less than 3 inches). When it appears to be the size of a plum, go ahead and harvest.
Remove the entire kohlrabi plant. Cut the main root off at the bottom of the bulb and compost it as long as it is a healthy plant. Remove also the leaf stalks above the bulb. Either eat the greens or compost them.
Kohlrabi can be stored in the fridge or cold cellar for a short amount of time. It is best eaten within a day or two of harvest.
Problems With Pests In Kohlrabi
Pests in kohlrabi are rarely serious. They are susceptible to the same pests as other vegetables in the cabbage family, but are generally easily taken care of. If your area is susceptible to these pests, use a row cover while growing, making sure that your edges are secured with rocks or other heavy safe objects.
I prefer not to spray anything I will in turn feed to my family, so my pest management involves either spraying them with a strong stream of water, picking off pests and/or eggs by hands, or removing the plants before pests spread.
Crop rotation is essential in promoting healthy plants. I use a 4 year rotation schedule, but only because I find it much easier than a 3 year rotation schedule which is what is generally advised.