Kohlrabi is stealing the limelight in gardens and kitchens alike and for good reason. This versatile veggie, with its alien-like appearance and sweet, crisp flavor, is not only a delight to grow but is also packed with health benefits. From choosing the right variety and planting at the optimal time, to taking care of pests and diseases, we’ve got you covered. Learn how to grow kohlrabi with the tips in this article.
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What is Kohlrabi?
Never heard of kohlrabi? You’re not alone. Kohlrabi (Brassica oleracea, Gongylodes group) is a relatively unknown and odd-looking bulbous vegetable in the Brassica family.
The word “kohlrabi” is German for “cabbage turnip”. There are two main types of kohlrabi; those with green or white skin and those with purple skin. Kohlrabi grows quickly; try interplanting it with slower-growing plants, and the kohlrabi will be ready for harvest before the other plants get large.
Rich in vitamins C and B6, potassium, and fiber, kohlrabi is a nutritious addition to any meal. Growing kohlrabi may seem daunting due to its unique structure – a bulbous stem that grows above ground – but don’t let this deter you!
Here are 5 Tips for How to Grow Kohlrabi:
1. Plant kohlrabi at the right time
Kohlrabi prefers cool temperatures and doesn’t mind a mild frost. Hot weather and dry soil result in tough, bitter-tasting woody bulbs.
The best time to sow kohlrabi seeds is 3 to 4 weeks before the last expected spring frost. Since kohlrabi is a cool-season crop, it prefers temperatures between 40°F and 75°F (4.4°C – 23.8°C). If you live in a place with mild winters, you can also plant kohlrabi in late fall for a winter harvest.
When growing kohlrabi in the low desert of Arizona:
- Start seeds indoors: August – December
- Plant seeds outside: September 15 – December
- Plant transplants outside: September 15 – January
For a continuous harvest, plant kohlrabi every 2-3 weeks.
2. Plant kohlrabi from seed or transplants
- To start seeds indoors, start seeds 6 to 8 weeks before planting. Sow seeds ¼ inch (0.6 cm) deep. Kohlrabi typically germinates in 3-10 days. Transplant in garden 6 to 8 inches apart.
- To direct sow outdoors, sow seeds 1 inch apart (2.54 cm) and ¼ inch (0.64 cm) deep. Thin plants to 6-8 inches apart (15-20 cm) when seedlings are 2-3 inches (5-8 cm) tall.
- For square-foot gardening, plant 4 kohlrabi per square.
- If you buy transplants, look for healthy plants with green leaves and uncrowded roots. Avoid buying overgrown plants or transplants with yellowed leaves or aphids.
3. Give kohlrabi what it needs to grow well
Kohlrabi thrives in well-drained soil rich in organic matter and compost. If your soil is heavy clay or sandy, add compost or well-rotted manure to improve its texture and nutrient content. The ideal pH range for kohlrabi is between 6.0 and 7.5.
Keep soil evenly moist throughout the growing season to keep kohlrabi from becoming woody. Aim for at least 1 inch (2.54 cm) of water per week, either from rain or irrigation. Mulch around the plants to conserve moisture and suppress weeds.
Although kohlrabi grows best in cool weather, it does best with at least 6 hours of sunlight.
Kohlrabi is fairly easy to grow and is usually relatively pest and disease free. Prevention is always better than cure. Practicing good sanitation, maintaining healthy soil, and monitoring your plants regularly can go a long way in keeping kohlrabi healthy.
Common kohlrabi pests and diseases, and how to handle them using organic methods:
- Cutworms: These caterpillars are nocturnal and can cause significant damage to your plants. They can be managed organically by introducing beneficial predators like birds and beneficial insects. Also, diatomaceous earth sprinkled around the base of the plants can deter these pests.
- Clubroot: This is a soil-borne disease that causes swollen and deformed roots. To prevent it, practice crop rotation, especially if you’ve recently had brassicas in the same spot.
- Black Rot: This bacterial disease can cause yellowing and wilting of leaves. To control it, ensure good air circulation around your plants and avoid overhead watering. Crop rotation is also crucial in preventing this disease.
- Aphids: These small insects suck sap from the plants, causing distorted growth and sometimes spreading disease. You can manage aphids by attracting beneficial insects, such as ladybugs and lacewings, which are natural predators of aphids.
- Cabbage Root Maggot: These maggots can cause wilting and stunting of the plant. To control them, use floating row covers to prevent the adult flies from laying eggs near your plants.
4. Harvest kohlrabi correctly
The plant matures in about 55-60 days for most varieties. You’ll know it’s time to harvest when the stem above the ground swells to about 2-3 inches (5-8 cm) in diameter. Don’t wait too long, as oversized kohlrabi can become woody and tough. However, for some preparations and German recipes, larger bulbs are desired.
Cut off bulbs just above ground level with a sharp knife, leaving roots in the ground. Leave some of the smaller side shoots attached to the main stem as these tender shoots can be eaten like broccoli florets.
To store and use later, separate the leaves from the bulbs and place them in a sealed plastic bag or container. Place the bulbs inside a plastic bag or container. Refrigerated bulbs will store well for up to 2 months.
Make a green powder “superfood” with extra leaves from brassicas after harvesting. Learn how in this blog post.
5. Enjoy kohlrabi in a variety of ways
Kohlrabi is delicious cooked or raw.
- To enjoy kohlrabi raw, peel away the thin skin and slice it into wedges like you would an apple. Add to salads, dip into soups, shred onto tacos – there are so many ways to enjoy kohlrabi!
- To cook kohlrabi, try roasting, steaming, or sautéing. Roasted kohlrabi is golden brown and slightly sweet. Steamed kohlrabi has a mild flavor that’s wonderful in salads and side dishes. Sautéed with butter and herbs makes for an excellent side dish.