Do you want to grow hydrangeas but live in a cold region?
Cultivars (horticultural selections) of smooth hydrangea (Hydrangea arborescens) and hardy hydrangea (Hydrangea paniculata) are your best choice! These underused hydrangeas reward you with beautiful white-fading to pale pink flowers June through September. Once the plants go dormant, their dry flower heads continue to add winter interest.
To increase your success choose a sunny location and prune your plants in winter to encourage new growth which will form flower buds next season.
What about big leaf or florist hydrangea (Hydrangea macrophylla)?
They can be grown in mild winter areas as extreme cold causes dieback to the ground. If plants freeze hard, they won’t flower as buds develop on previous year’s growth. Big leaf hydrangeas are also affected by soil conditions. In acidic soils flowers turn blue while in neutral to alkaline soils the flowers will change to pink or red. In the florist industry, growers manipulate soil pH to create the exquisite colors you see.