How to Grow Kohlrabi
Brassica oleracea var. gongylodes
When to Start
Direct sow outdoors as soon as soil reaches 6°C — typically early to mid spring. Can also be started indoors 4 weeks earlier for a head start.
Don't know your frost date? Find it here →
Growth Stages
Approximate days from start
Care Essentials
- Light balanced feed at sowing. Needs consistent moisture.
- Quick-growing (8–10 weeks). Mild, sweet flavour — eat raw or cooked. Purple varieties are more ornamental.
Companion Planting
—
Growing Conditions
Get a personalized schedule for Kohlrabi based on your exact frost dates
Start planning freeEnter your last frost date to see your dates
- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
Want your full season plan with reminders? Try Leaftide free
Spacing & Planting
| Plant spacing | 20 cm |
| Row spacing | 30 cm |
| Sow depth | 0.5 cm |
| Mature height | 40 cm |
| Mature spread | 30 cm |
Fast crop; keep growing steadily to avoid woody bulbs.
Care Guide
- Feeding
- Light balanced feed at sowing. Needs consistent moisture.
- Watch for
-
- Flea beetle
- Cabbage root fly
- Club root
Pests & Diseases
Pest Flea Beetle
Identification: Tiny round shot-holes peppered across leaves, small shiny black beetles that jump when disturbed
- Cover with fine insect mesh immediately after sowing or planting
- Water regularly to encourage fast growth through vulnerable stage
- Sticky traps placed near plants
- Pyrethrum-based spray as a last resort
Pest Cabbage Root Fly
Identification: Wilting plants despite adequate watering, white maggots around roots when lifted
- Brassica collars around stems at planting to prevent egg-laying
- Fine insect mesh over the crop
- Companion plant with strong-scented herbs
- No effective chemical treatments available to home gardeners
Pest Cabbage White Caterpillars
Identification: Large ragged holes in leaves, green or yellow-black caterpillars visible, clusters of yellow eggs on leaf undersides
- Cover with insect mesh from planting
- Hand-pick caterpillars and eggs regularly
- Bacillus thuringiensis (Bt) spray
- Limited options for edible crops
Disease Clubroot Plasmodiophora brassicae
Symptoms: Stunted growth, wilting in warm weather despite moist soil, swollen and distorted roots
Treatment: No cure once established. Remove and destroy affected plants. Do not compost.
Prevention: Lime soil to pH 7.0-7.5. Practice strict 4-year brassica rotation. Improve drainage. Start plants in modules with clean compost.
Disease Downy Mildew Hyaloperonospora parasitica
Symptoms: Yellow patches on upper leaf surfaces with grey-white fuzzy growth underneath
Treatment: Remove affected leaves promptly. Improve air circulation.
Prevention: Space plants well for airflow. Avoid overhead watering. Water in the morning so foliage dries quickly.
Growing Conditions
| Min. soil temperature | 6°C |
| Germination temperature | 15–25°C |
| Base growth temperature | 4°C |
| Min. daylength to start | 9h |
| Photoperiod sensitivity | long day |
Frequently Asked Questions
- How far apart should I plant Kohlrabi?
- Plant Kohlrabi 20cm apart with 30cm between rows.
- When can I harvest Kohlrabi?
- Kohlrabi is ready to harvest approximately 35 days after transplanting.
- Is Kohlrabi frost hardy?
- Kohlrabi is classified as Hardy.
Plan Kohlrabi in your garden — get personalized frost-date scheduling
Start planning free