Poznań, Poland · 52.41°
When to plant hydrangeas in Poznań
The Poznań dates are calculated from the observed last spring frost — a 2016–2025 mean of 18 April — rather than from a latitude estimate or a national calendar. The frost-free season here averages 212 days.
Season anchorobserved 2016–2025
Last spring frost: 18 April · latest 10 May
First autumn frost: 16 November · earliest 31 Oct
Frost-free season: 212 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 (10 May). Use it for tender crops you cannot re-sow.
The year in Poznań
What can move the date
Soil pH sets the colour of mophead types: acid soil gives blue, alkaline gives pink, and white varieties ignore both. Know which species you have before pruning — cutting a mophead in spring removes every flower bud.
Final spacing: 120 × 150 cm. Soil: pH 5–6.5.
Problems in Poznań
Each has its locally favourable conditions counted month by month, from the weather archive for this city.
Full guide: hydrangeas diseases and pests →