Blasts of extreme cold and ice damage can kill flower buds. In USDA Zone 5 and colder, susceptible hydrangeas flower best ...
which range from USDA zones 3 to 9 for panicle and smooth hydrangeas, and zones 5 to 9 for bigleaf and oakleaf hydrangeas. However, these hardiness zones apply to overall plant survival ...
Two hydrangea species are considered native for U.S. East Coast and suitable for U.S.D.A Hardiness Zones 5-7. They are: H. quercifolia (oakleaf hydrangea) and, H. arborescens (smooth or wild hydrangea ...