Toronto, Ontario
When to plant onion in Toronto
Station data · 88% confidence cool seasonhardy to frost
- Harvestmid JulyJul 17 – Aug 6 · 79% conf.
- Start seeds indoorslate FebruaryFeb 28 – Mar 21 · 84% conf.
- Transplant outdoorsmid AprilApr 18 – May 9 · 88% conf.
The growing window at a glance
Frost-free growing season · 150 daysFrost risk (before May 9 / after Oct 6)
Onion at a glance in Toronto
- Needs soil above 10°C to germinate well.
- Days to maturity: 90–110 days.
- Climate zone: Continental, warm summer (Dfb).
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 Toronto?
Expect to harvest from around mid July (Jul 17–Aug 6) in Toronto, based on its local frost dates. Confidence 79%.
When should I start onion seeds indoors in Toronto?
Start seeds indoors around late February (Feb 28–Mar 21) in Toronto, based on its local frost dates. Confidence 84%.
When can I transplant onion outdoors in Toronto?
Transplant outdoors around mid April (Apr 18–May 9) in Toronto, based on its local frost dates. Confidence 88%.
How long is the growing season in Toronto?
Toronto has roughly 150 frost-free days, which is enough time to grow onion to maturity outdoors.