When to Plant Onion in Perth, Mediterranean Guide
Sow July to September. Right now in September you can sow.
Also called spring onion, scallion, shallot (the Australian name for spring onion).
Published · Last reviewed · By Garden Buddy
Growing advice is reviewed by hand. Planting dates, current conditions and prices on this page update daily.
This Onion guide is written for the Mediterranean zone, which takes in Perth, Adelaide and Bunbury. Somewhere else? Your postcode picks the right one.
Not your zone? Cairns Brisbane Sydney Melbourne Canberra Alice Springs
Also handy: will it frost this week? and what grows in shade.
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 for Mediterranean
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| - | - | - | - | - | - | S/T/D | S/T/D | S/T/D | - | - | - |
S = Seed Tray T = Transplant D = Direct Sow
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Current Growing Conditions
Soil temperature: 15.9°C (optimal range: 8–30°C) ✓ Ready to plant
Modelled from Open-Meteo forecast (Perth), not a live sensor.
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.
Worth growing?
A 2.4 m × 1.2 m bed fits 72 plants, about $29 worth at today’s Aldi, Coles and Woolworths prices, checked today.
That is roughly 11 kg at $2.66 a kilo.
Draw your onion bed → No account needed.
Common Onion Pests in Mediterranean 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.
Where to next
Supermarket Price
Current average retail: $2.66/kg (12-month range: $1.99–$5.20)
Grow your own and save on grocery bills.
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Open the planting dashboard Join Garden BuddyCommon Questions About Onion
When do you plant onion in Australia?
It depends on your climate zone, not the calendar month alone. Planting months by zone:
- Tropical (Cairns): Apr, Jun to Jul
- Subtropical (Brisbane): Feb, Apr to Jun, Aug
- Warm Temperate (Sydney): Jul to Sep
- Cool Temperate (Melbourne): Jul to Sep
- Cold / Highland (Canberra): Aug to Sep
- Arid / Semi-Arid (Alice Springs): Feb, Apr to Aug
- Mediterranean (Perth): Jul to Sep
Does onion grow all year round in Perth?
No. In the Mediterranean zone the planting months are Jul to Sep. Outside that window it either bolts, sulks or gets cut down by the weather.
What else is onion called?
Onion is the usual Australian name. Overseas seed packets and recipes call it spring onion, scallion, shallot (the Australian name for spring onion). Same plant, same growing advice.
Which zone am I in?
Type your postcode into the box under the heading and the page tells you, and links this crop in your own zone if it differs. Or look it up on the grow zone map. This page is the Mediterranean zone, Perth is its reference city.