Toronto, Canada · 43.65°
When to plant dahlias in Toronto
The Toronto dates are calculated from the observed last spring frost — a 2016–2025 mean of 25 April — rather than from a latitude estimate or a national calendar. The frost-free season here averages 197 days.
Season anchorobserved 2016–2025
Last spring frost: 25 April · latest 15 May
First autumn frost: 8 November · earliest 30 Oct
Frost-free season: 197 days · 10 complete years
These come from the ERA5 reanalysis on a roughly 9 km grid, so they describe the area rather than your plot. A hollow, a frost pocket or an exposed site regularly runs several degrees colder, so use the cautious date for a decision you cannot undo.
Frost date estimator →Local calendar windows
The cautious column is calculated from the latest frost recorded in the period (15 May). Use it for tender crops you cannot re-sow.
The year in Toronto
What can move the date
Tubers rot if planted into cold, wet ground, so wait until the frost risk has passed. Stake at planting time, not later — driving a stake in beside a grown plant spears the tuber.
Final spacing: 50 × 70 cm. Soil: pH 6–7.5.
Problems in Toronto
Each has its locally favourable conditions counted month by month, from the weather archive for this city.
Full guide: dahlias diseases and pests →