When to Plant Kohlrabi in Brisbane — Subtropical Guide

Kohlrabi

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: 23.6°C (optimal range: 10–30°C) ✓ Ready to plant

How to Grow Kohlrabi in Subtropical Australia

When to Plant

February to August. Autumn and winter are the prime growing season. Spring sowings bolt in October heat.

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

Subtropical Growing Tips for Kohlrabi

Recommended Varieties

  • White Vienna
  • Purple Vienna
  • Kolibri F1

Key Challenges

  • Bolting in warm weather
  • Cabbage white butterfly year-round
  • Humidity-driven diseases

Pro Tips

  • SEQ gardeners: autumn-winter is your window - February to July
  • Succession sow every 2-3 weeks for continuous harvest
  • Purple Vienna is more heat-tolerant than White Vienna

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.

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