When to Plant Onion in Perth — Mediterranean Guide

Onion

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.

Current Growing Conditions

Soil temperature: 21.9°C (optimal range: 8–30°C) ✓ Ready to plant

How to Grow Onion in Mediterranean Australia

When to Plant

Sow April-June, transplant June-August. Long-day and intermediate varieties both work well. 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

Mediterranean Growing Tips for Onion

Recommended Varieties

  • Pukekohe Long Keeper (long-day)
  • Creamgold (intermediate)
  • Brown Spanish
  • White Spanish
  • Red Globe

Key Challenges

  • Hot, dry spring causing premature bulbing if not established
  • Downy mildew in wet winters
  • Storage quality depends on thorough curing

Pro Tips

  • Perth and Adelaide latitudes suit long-day varieties well
  • Plant early enough for good leaf growth before bulbing starts
  • The dry summers are ideal for curing and storing onions

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.

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,.