When to Plant Kohlrabi in Cairns — Tropical Guide
Photo: Wikimedia Commons
Kohlrabi is technically not a root vegetable - the edible part is a swollen stem that forms above ground. Fast-growing (55-70 days), mild-flavoured, and versatile in the kitchen, kohlrabi is an underused gem in Australian gardens. It thrives in cool weather, handles light frost, and is one of the best brassicas for beginners. Both the bulb and leaves are edible.
Current Growing Conditions
Soil temperature: 25.2°C (optimal range: 10–30°C) ✓ Ready to plant
How to Grow Kohlrabi in Tropical Australia
When to Plant
March to July (dry season only). Kohlrabi bolts quickly in hot, humid conditions. Plant at the start of the dry season for best results.
- Soil
- Rich, well-drained soil with plenty of organic matter. Prefers neutral to slightly alkaline soil. Dig in compost and well-rotted manure before planting. Add lime to acidic soils (critical for preventing clubroot).
- pH Range
- 6.5-7.5
- Sunlight
- Full sun (6+ hours). Tolerates light shade, especially in warmer zones where afternoon shade prevents bolting.
- Spacing
- 20cm apart, 35cm between rows
- Watering
- Consistent, even moisture throughout growth. Water deeply 2-3 times per week. Inconsistent watering causes the stem bulb to become woody and split. Drip irrigation preferred.
Companion plants: Beetroot, Celery, Cucumber, Dill, Lettuce, Onion
Avoid planting near: Strawberry, Tomato, Runner Bean
Tropical Growing Tips for Kohlrabi
Recommended Varieties
- White Vienna
- Purple Vienna
Key Challenges
- Rapid bolting in heat
- Caterpillar pressure year-round
- Clubroot in acidic tropical soils
Pro Tips
- Grow fast - kohlrabi matures in 55-70 days which fits the dry season
- Net against caterpillars from day one
- Harvest at tennis ball size - do not let them get too large in warm conditions or they become woody
Harvesting Kohlrabi
When ready: Stem bulb is 6-8cm diameter (tennis ball size) for standard varieties. Bulb should feel firm and smooth. Harvest promptly - overgrown bulbs (>10cm for standard varieties) become woody and fibrous. Exception: Superschmelz stays tender up to 20cm.
How to harvest: Cut stem just below the bulb with a sharp knife, or pull the entire plant. Trim off leaves (save for cooking - they are edible). Trim the root.
Get the Full Interactive Guide
Open the interactive planting dashboard with real-time weather, all pest alerts, and garden tracking.
Join Garden Buddy for premium features: disease management, seed saving, preservation guides,.