Kohlrabi is a quick, cool-season crop in the cabbage family. It forms a crisp, mild, slightly sweet round bulb just above the soil, and the leaves are edible too. Most varieties are ready about two months after sowing, so it fits easily between other crops. This page covers when to plant, spacing, care, common problems and how to harvest kohlrabi at its best.
Kohlrabi at a glance
| Type | Vegetable |
|---|---|
| Season | Cool-season |
| Sun | Full sun |
| Plant spacing | 6 in |
| Row spacing | 12 in |
| Per square foot | 4 |
| Seed depth | ½ in |
| Days to maturity | 55–70 from seed |
| How to start | Kohlrabi grows best when days are cool, roughly 60 to 70°F. |
| Water | 1 in per week |
These are the same numbers our plant spacing, square foot and harvest date calculators use. See every crop in the plant database.
When to plant kohlrabi
Kohlrabi grows best when days are cool, roughly 60 to 70°F. Sow seed outdoors 2 to 4 weeks before your last spring frost, and sow again 6 to 8 weeks before your first fall frost for a second crop. Heat is its enemy: bulbs grown in summer turn tough and woody. Young plants handle a light frost well.
Look up your dates with the frost dates by ZIP code tool, then count back or forward with the planting calendar.
How to plant kohlrabi
- Prepare the bed. Choose full sun and loose, fertile, well-drained soil with a pH of about 6.0 to 7.5. Mix in a few inches of compost before sowing.
- Sow shallow. Plant seeds about half an inch deep. Seeds sprout in 5 to 10 days.
- Thin early. Thin seedlings to about 6 inches apart, using the spacing in the table above. Crowded plants make small, woody bulbs.
- Stagger sowings. Sow a short row every 2 weeks so the harvest does not all arrive at once.
Caring for kohlrabi
Steady moisture is the key to tender kohlrabi. Give plants about an inch of water a week, and do not let the soil swing between dry and soaked, which causes cracked or woody bulbs. The garden watering calculator turns that into gallons for your bed. Mulch lightly to hold moisture and keep the soil cool.
Feed once with compost or a balanced fertilizer when plants are about 4 inches tall. Weed gently, because the roots are shallow. Cover young plants with row cover to keep out cabbage moths and flea beetles.
Companion plants
| Grow nearby | Beets, onions, lettuce, cucumbers, and herbs such as dill, mint and chamomile |
|---|---|
| Keep apart | Tomatoes, pole beans, peppers and strawberries (said to compete or stunt growth) |
Aromatic herbs planted nearby are said to confuse cabbage-family pests, and fast crops like radishes and lettuce make good neighbors because they finish before kohlrabi needs the space. Check other pairings with the companion plant finder.
Common problems
| Problem | What you see | What to do |
|---|---|---|
| Woody or tough bulbs | Fibrous, stringy flesh when cut | Usually heat, slow growth or leaving bulbs too long. Harvest at 2 to 3 inches across and keep watering even. |
| Cracked bulbs | Splits in the skin | Swings between dry and wet soil. Water evenly and mulch. |
| Cabbage worms | Ragged holes in leaves, green caterpillars | Pick them off by hand or cover plants with row cover. See the pest identifier. |
| Flea beetles | Many tiny shot-like holes in leaves | Use row cover from sowing. Healthy plants outgrow light damage. |
| Bolting | A flower stalk forms and the bulb stops swelling | Caused by heat or a cold snap on young plants. Sow at the right time and pull bolted plants. |
Not sure what you are looking at? The plant problem identifier ranks likely causes from the symptoms you see.
When and how to harvest
Harvest kohlrabi when the bulb is 2 to 3 inches across, roughly the size of a golf ball to a tennis ball. At that size it is crisp and sweet. Large-type varieties such as Kossak can stay tender at 5 inches or more, but most kinds turn woody when oversized. Cut the stem just below the bulb with a knife, then trim off the leaves and root.
The leaves are edible too; cook them like collard greens. Peel the bulb and eat it raw in slaws and salads or roast, steam or stir-fry it. Bulbs keep in the refrigerator for 2 to 3 weeks, and a fall crop can wait in the garden through light frosts.
Plan your kohlrabi
- Plant spacing calculator: how many plants fit your bed
- Planting calendar: sowing and transplant dates for your frost dates
- Frost dates by ZIP code: your last spring and first fall frost
- Harvest date calculator: when your crop will be ready
Frequently asked questions
How far apart should I plant kohlrabi?
Space kohlrabi 6 inches apart in rows 12 inches apart. In a square foot garden, plant 4 per square foot.
How deep do I plant kohlrabi seeds?
Sow kohlrabi seeds about half an inch deep and thin seedlings to 6 inches apart.
How long does kohlrabi take to grow?
Most varieties are ready 55 to 70 days after sowing, and early types in as little as 45 days. Harvest when bulbs are 2 to 3 inches across.
How much water does kohlrabi need?
About 1 inch of water a week, from rain and watering combined. Keep the soil evenly moist to prevent woody or cracked bulbs.
Can you eat kohlrabi leaves?
Yes. Kohlrabi leaves are edible and taste like mild collard greens. Pick a few from each plant without stripping it, since the leaves feed the growing bulb.
Why is my kohlrabi woody?
Kohlrabi turns woody when it grows slowly in heat, gets uneven water or stays in the ground past the ideal 2 to 3 inch size. Harvest sooner and water evenly.