Perth, Western Australia
When to plant onion in Perth
Station data · 80% confidence cool seasonhardy to frost
- Harvestearly OctoberOct 9 – Oct 29 · 72% conf.
- Start seeds indoorslate MayMay 23 – Jun 13 · 76% conf.
- Transplant outdoorsmid JulyJul 11 – Aug 1 · 80% conf.
The growing window at a glance
Frost-free growing season · 343 daysFrost risk (before Aug 1 / after Jul 10)
Onion at a glance in Perth
- Needs soil above 10°C to germinate well.
- Days to maturity: 90–110 days.
- Climate zone: Mediterranean, hot summer (Csa).
Frost dates are probabilities, not guarantees. Your garden's microclimate — slopes, walls, urban heat, cold pockets — can shift these dates by a week or more. Use them as a confident starting point, then watch your local forecast.
Frequently asked
When will onion be ready to harvest in Perth?
Expect to harvest from around early October (Oct 9–Oct 29) in Perth, based on its local frost dates. Confidence 72%.
When should I start onion seeds indoors in Perth?
Start seeds indoors around late May (May 23–Jun 13) in Perth, based on its local frost dates. Confidence 76%.
When can I transplant onion outdoors in Perth?
Transplant outdoors around mid July (Jul 11–Aug 1) in Perth, based on its local frost dates. Confidence 80%.
How long is the growing season in Perth?
Perth has roughly 343 frost-free days, which is enough time to grow onion to maturity outdoors.