Can a Hydrangea that was purchased for Easter and has been an inside plant be transplanted outdoors in Zone 5?
Certified GKH Gardening Expert
Yes, it can be transplanted, but I would put it off until fall if at all possible. However, as long as the plant is properly acclimated beforehand and the temps are not too hot/cold, you can still go ahead and put your hydrangea in the ground now. In other words, if hydrangeas are hardy in your area, they may be planted in the spring after all chance of frost is gone and preferably before the hot conditions of summer arrive. They must also be conditioned to the outdoors gradually. Be sure to place it in a suitable location and give it plenty of water deeply until the plant establishes itself.
These articles should help: https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/growing-hydrangeas-hydrangea-care-guide.htm