Fall is the optimum time to plant many shrubs and trees ... variety that isn’t quite hardy in your USDA Zone—a hydrangea rated for Zones 5-9 in your Zone 4 location, for example—is fine ...

Long-lived hydrangea shrubs do have some common issues to ... a 'Limelight' panicle hydrangea is hardy in USDA zones 3 to 9, while a 'Nikko Blue' bigleaf hydrangea is hardy in zones 6 to 9).