For the most part, hydrangeas can be planted any time during the growing season, provided the person planting them will be around during the hottest part of the year to monitor them for water needs and other possible stresses. The ideal time is spring, once the danger of frost has passed, followed by autumn in most areas. Here, we'll break it down a little further, with suggestions by hydrangea type and hardiness zone (find your hardiness zone here).
|Hydrangea type||Zones 3 & 4||Zones 5 & 6||Zones 7, 8, and 9|
|Bigleaf, bracted, mountain||n/a, not hardy||spring, early-mid summer||early-mid spring or autumn|
|Climbing, false hydrangea-vine||n/a, not hardy||spring, summer, or early autumn||early-mid spring or autumn|
|Oakleaf||n/a, not hardy||spring, summer, or early autumn||early-mid spring or autumn|
|Panicle/peegee||spring, summer, or early autumn||spring, summer, or early autumn||early-mid spring or autumn|
|Smooth/'Annabelle'||spring, summer, or early autumn||spring, summer, or early autumn||early-mid spring or autumn|
Remember, these are just suggestions that make the planting and establishment process as stress-free as possible for both you and your hydrangea; they aren't set-in-stone rules. The real key is to minimize the stress the plant experiences, whether from heat, cold, water, or humidity, so that it can quickly grow roots in its new home.