When to Plant Radish in Cairns — Tropical Guide
Photo: Wikimedia Commons
Radishes are the fastest-growing root vegetable, with some varieties ready in as little as 4 weeks. They are ideal for beginners, succession planting, and filling gaps between slower crops. Summer, winter, and oriental types offer year-round harvesting potential across most Australian zones.
Current Growing Conditions
Soil temperature: 25.2°C (optimal range: 8–30°C) ✓ Ready to plant
How to Grow Radish in Tropical Australia
When to Plant
Plant year-round, but best results from March-August (dry season). Summer sowings bolt quickly in heat and long days. Daikon types suit the tropical dry season well.
- Soil
- Friable, well-drained soil with good moisture retention. Avoid heavy clay. Compost or aged manure improves results but do not use fresh manure which causes forking.
- pH Range
- 6.0-7.0
- Sunlight
- Full sun in cool months; light afternoon shade in summer to prevent bolting
- Spacing
- 5cm apart, 25cm between rows
- Watering
- Consistent moisture is critical. Radishes grown with irregular water become woody, pithy, and hot. Water lightly every 1-2 days in dry weather. Mulch to retain soil moisture.
Companion plants: Lettuce, Spinach, Carrot (as trap crop for flea beetle), Peas, Nasturtium
Avoid planting near: Hyssop, Other brassicas (to reduce shared pest load)
Tropical Growing Tips for Radish
Recommended Varieties
- White Icicle
- Cherry Belle
- French Breakfast
- Daikon (Oriental winter radish)
Key Challenges
- Rapid bolting in summer heat
- Flea beetle and caterpillar pressure year-round
- Pithy roots in hot weather
Pro Tips
- Focus on the dry season for best quality roots
- Harvest early (3-4 weeks) before roots become pithy
- Use shade cloth (30-50%) for summer sowings
Harvesting Radish
When ready: Round varieties: shoulder visible at soil level, 2-3cm diameter. Pull one to check. Summer types: harvest at 4-6 weeks before they become pithy. Winter/daikon types: harvest at 8-10 weeks when 15-25cm long.
How to harvest: Grasp foliage near the crown and pull gently. Water the bed beforehand if soil is dry. For daikon/winter types, loosen soil alongside the root with a fork first.
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