Cultivation

Freezing tolerance of Hydrangea macrophylla

Hydrangea macrophylla (Thunb.) Ser.

Hydrangea macrophylla is highly sensitive to sub-zero temperatures, which cause irreversible damage to tissues and flower buds formed on the previous year's shoots.

In the reference 49 varieties crop Bigleaf hydrangea, where this is mentioned in the description.

Flower buds of this hydrangea species are formed on last year's shoots and are at critical risk when temperatures drop to -2...-5 °C. Exposure to frost causes water within the cells to form ice crystals, which rupture the plant's cytoplasm and vascular system, making flowering in the current season impossible.

External signs of tissue damage include loss of turgor, blackening of leaves, and bud death. Unlike species that bloom on current-season growth, Hydrangea macrophylla requires mandatory protection or specialized wintering conditions to prevent its terminal buds from freezing.

General information about the subject — on the page Suitability for freezing.

Sources8

Varieties of Bigleaf hydrangea mentioned in the description

Selection based on the description text, not on official evaluation: these data are absent from registers. For specific variety details, please refer to its profile.