Kohlrabi grows best when planted in cool weather and harvested before the bulb becomes woody. If you’re looking for a unique, fast-growing vegetable that adds crunch to salads and slaws, learning how to grow kohlrabi is a smart move. This brassica relative is easy to care for and rewards you with edible stems that look like alien spaceships.
You don’t need a huge garden to succeed. A small raised bed or even a deep container works fine. Let’s walk through everything from seed to harvest.
What Is Kohlrabi And Why Grow It?
Kohlrabi is a member of the cabbage family. The part you eat is the swollen stem that grows just above the soil line. It tastes like a mild, sweet turnip with a broccoli-like crunch.
It’s packed with vitamin C and fiber. Plus, it grows fast—some varieties are ready in 45 days. That makes it perfect for impatient gardeners.
How To Grow Kohlrabi: Complete Step-By-Step Guide
Now let’s get into the details. Follow these steps and you’ll have tender bulbs in no time.
Choose The Right Variety
There are two main types: green and purple. Both taste the same, but purple varieties are more cold-tolerant. Popular choices include ‘Early White Vienna’, ‘Purple Vienna’, and ‘Korridor’.
- Early White Vienna – fast, 50 days, classic green
- Purple Vienna – cold hardy, 60 days
- Korridor – slow to bolt, good for warm weather
- Gigante – huge bulbs, 80 days, best for storage
When To Plant Kohlrabi
Kohlrabi is a cool-season crop. Plant it in early spring, about 4 weeks before your last frost date. You can also plant in late summer for a fall harvest.
Soil temperature should be at least 45°F (7°C). Seeds germinate best between 50°F and 75°F. If it gets too hot, the bulbs become woody and tough.
Prepare The Soil
Kohlrabi likes rich, well-draining soil with a pH between 6.0 and 7.5. Work in 2 inches of compost before planting. Avoid fresh manure—it can cause forked roots.
If your soil is heavy clay, consider raised beds. Kohlrabi bulbs push up as they grow, so loose soil helps them develop evenly.
Sowing Seeds Directly
Direct sowing is best. Kohlrabi doesn’t transplant well because its taproot is delicate. Sow seeds ¼ inch deep, 1 inch apart in rows spaced 12 inches apart.
- Make a shallow furrow with your finger
- Drop seeds every 1 inch
- Cover lightly with soil
- Water gently with a fine spray
- Keep soil moist until seedlings emerge (5-10 days)
Thin seedlings to 4-6 inches apart once they have two true leaves. Crowded bulbs stay small and misshapen.
Watering Needs
Kohlrabi needs consistent moisture. Give it 1-1.5 inches of water per week. If the soil dries out, the bulbs become tough and bitter.
Use drip irrigation or water at the base to avoid wet leaves. Wet foliage invites fungal diseases like downy mildew.
Fertilizing For Best Growth
Kohlrabi is a moderate feeder. Mix a balanced 10-10-10 fertilizer into the soil before planting. Side-dress with compost tea or fish emulsion when bulbs start to swell.
Avoid too much nitrogen. It makes leaves grow big but bulbs stay small. Phosphorus and potassium are more important for bulb development.
Mulch And Weed Control
Apply a 2-inch layer of straw or grass clippings around plants. Mulch keeps soil cool, retains moisture, and blocks weeds. Weeds compete for nutrients and stunt growth.
Hand-pull weeds carefully. Kohlrabi roots are shallow and easily disturbed.
Pest And Disease Management
Common pests include cabbage worms, aphids, and flea beetles. Use row covers to protect young plants. For aphids, spray with insecticidal soap or a strong stream of water.
- Cabbage worms – handpick or use Bt (Bacillus thuringiensis)
- Flea beetles – use diatomaceous earth or neem oil
- Slugs – set beer traps or use copper tape
- Clubroot – rotate crops, avoid planting in infected soil
Diseases are rare if you practice crop rotation. Don’t plant kohlrabi where other brassicas (cabbage, broccoli, kale) grew in the past 3 years.
Harvesting Kohlrabi At The Right Time
Harvest when bulbs are 2-3 inches in diameter. That’s about the size of a tennis ball. Bigger bulbs get woody and lose flavor.
Cut the stem just below the bulb with a sharp knife. Remove leaves and store them separately—they’re edible too. Use bulbs within a week for best taste.
If you wait too long, the skin becomes tough and the inside turns fibrous. You can still eat oversized bulbs, but peel them first and cook them longer.
How To Store Kohlrabi
Store unwashed bulbs in a plastic bag in the fridge. They last 2-3 weeks. Remove leaves first—they draw moisture from the bulb.
You can also blanch and freeze kohlrabi. Cut into cubes, blanch for 2 minutes, then freeze in airtight bags. Frozen kohlrabi keeps for 6 months.
Growing Kohlrabi In Containers
Kohlrabi does well in pots. Choose a container at least 12 inches deep and wide. Fill with quality potting mix mixed with compost.
Space plants 4 inches apart in the container. Water more frequently—pots dry out faster. Fertilize every 2 weeks with a liquid fertilizer.
Harvest the same way. Container-grown bulbs are often smaller but just as tasty.
Common Problems And Solutions
Even experienced gardeners hit snags. Here’s what to watch for:
- Bulbs not forming – too much nitrogen or overcrowding. Thin plants and reduce fertilizer.
- Cracked bulbs – irregular watering. Keep soil consistently moist.
- Woody texture – harvested too late or heat stress. Pick earlier and plant in cool weather.
- Bolting (going to seed) – temperature swings or stress. Use row covers to moderate temps.
- Yellow leaves – nutrient deficiency or overwatering. Check soil drainage and add compost.
Companion Planting For Kohlrabi
Good neighbors help kohlrabi thrive. Plant it near beets, onions, and herbs like dill and chamomile. These repel pests and improve flavor.
Avoid planting near tomatoes, pole beans, or strawberries. They compete for nutrients or attract similar pests.
Best Companion Plants
- Beets
- Onions
- Dill
- Chamomile
- Mint (in a container to prevent spreading)
Worst Companion Plants
- Tomatoes
- Pole beans
- Strawberries
- Other brassicas (cabbage, broccoli, kale)
Extending The Growing Season
You can grow kohlrabi in spring and fall. For a fall crop, plant seeds 8-10 weeks before your first frost. Kohlrabi tolerates light frost and actually tastes sweeter after a chill.
Use cold frames or row covers to protect plants from hard freezes. In mild climates, you can overwinter kohlrabi with heavy mulch.
Nutritional Benefits Of Kohlrabi
Kohlrabi is low in calories but high in nutrients. One cup provides 100% of your daily vitamin C needs. It also has potassium, copper, and fiber.
Eat it raw in salads, slaws, or with dip. Cook it by roasting, steaming, or stir-frying. The leaves are edible too—use them like kale or collards.
Frequently Asked Questions
Can I Grow Kohlrabi In Hot Weather?
Kohlrabi prefers cool weather. In hot climates, plant in early spring or fall. Use shade cloth if temps exceed 80°F. Hot weather makes bulbs woody.
How Long Does Kohlrabi Take To Grow From Seed?
Most varieties take 45-60 days from seed to harvest. Fast-growing types like ‘Early White Vienna’ are ready in 45 days.
Why Are My Kohlrabi Bulbs Not Getting Big?
Common reasons: overcrowding, too much nitrogen, or insufficient water. Thin plants to 4-6 inches apart, use balanced fertilizer, and water consistently.
Can I Eat Kohlrabi Leaves?
Yes, leaves are edible and nutritious. Use them raw in salads or cooked like spinach. They have a mild broccoli flavor.
Do I Need To Peel Kohlrabi Before Eating?
Small bulbs (2 inches) have tender skin you can eat. Larger bulbs have tough skin—peel it off with a knife or vegetable peeler.
Final Tips For Success
Start with quality seeds from a reputable supplier. Keep soil moist but not soggy. Harvest early for the best texture. Rotate crops yearly to prevent disease.
Kohlrabi is forgiving for beginners. Once you taste your first homegrown bulb, you’ll wonder why you didn’t try it sooner. The crisp, sweet flavor is worth the small effort.
Remember, the key is cool weather and consistent care. Plant at the right time, give it space, and don’t let it get too big. Follow this guide and you’ll have a bumper crop of tender, tasty kohlrabi.
Now go grab some seeds and get planting. Your garden—and your taste buds—will thank you.