When to Plant Onion in Brisbane — Subtropical Guide
Photo: Wikimedia Commons
Onions are a staple in Australian kitchens and one of the most widely grown alliums in home gardens. Bulb formation is triggered by day length, making variety selection critical based on latitude. Short-day types suit northern Australia, while long-day types perform best in southern regions.
Planting Calendar
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| — | S | — | T | T/D | S | — | T | — | — | — | — |
S = Seed Tray T = Transplant D = Direct Sow
Current Growing Conditions
Soil temperature: 23.6°C (optimal range: 8–30°C) ✓ Ready to plant
How to Grow Onion in Subtropical Australia
When to Plant
Sow seed March-May or transplant seedlings April-June. Short-day varieties best. Some intermediate-day types will bulb in SEQ. Harvest November-January.
- Soil
- Well-drained, fertile loam enriched with compost. Avoid heavy clay or freshly manured soil which causes forking and soft bulbs.
- pH Range
- 6.0-7.0
- Sunlight
- Full sun (minimum 6 hours direct)
- Spacing
- 12cm apart, 30cm between rows
- Watering
- Consistent moisture during bulb development. Water deeply once or twice weekly. Reduce watering as tops begin to fall over (curing signal). Overhead irrigation can reduce thrips but increases fungal r
Companion plants: Carrot, Beetroot, Lettuce, Chamomile, Strawberry
Avoid planting near: Beans, Peas, Asparagus, Sage
Subtropical Growing Tips for Onion
Recommended Varieties
- Early Lockyer White (short-day)
- Gladalan Brown (short-day)
- Red Tropicana (short-day)
- Creamgold (intermediate)
- Hunter River Brown
Key Challenges
- Summer humidity causing storage rot
- Thrips during dry spring weather
- Bolting if planted too early and exposed to cold
Pro Tips
- Short-day varieties are the safest choice for reliable bulbing
- Plant after the hottest weather has broken (March onwards)
- Ensure excellent drainage - onions hate wet feet
Harvesting Onion
When ready: Tops fall over naturally and begin to yellow. Bulb skin is papery and dry. Neck tissue is thin and soft. Do not push tops over prematurely as this reduces storage life.
How to harvest: Loosen soil with a fork and lift gently. Do not pull by the tops. Lay on their side in the garden for 1-2 days if weather is dry, then move to a well-ventilated, shaded area for 2-4 weeks to cure fully. Roots and tops are trimmed after curing.
Common Onion Pests in Subtropical Zones
Organic prevention: Rotate allium crops on a 3-year cycle. Remove crop residues after harvest. Avoid planting near cereal crops which harbour thrips. Maintain weed-free beds.
Supermarket Price
Current average retail: $6.21/kg (range: $1.99–$21.33)
Grow your own and save on grocery bills.
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