|why don't my hydrange plants flower?|
|The two most common reasons for lack of blooms on bigleaf hydrangeas (Hydrangea macrophylla) are winter damage and improper pruning. Most of these hydrangeas bloom only on old wood that grew the year before. If the stems are winter killed, there will be no blooms. And if you prune in fall, winter or spring there will be no blooms because the flowering wood has been trimmed off. Spring frosts can also damage the flower buds. Be sure to cover the plant in spring if a frost threatens after the buds have begun to swell.
Your zip code places you in zone 5, so I suspect the problem is winter cold damage in this case. You might try moving it to a more sheltered location with protection from winter wind and also insulate it from the cold every winter. To do that, erect a cylinder of wire mesh around the plant and fill it with nonpacking material such as dry oak leaves or loose dry straw. Cover the top with a tarp to keep it dry, but allow some gaps for air circulation so there is no condensation inside. Put this on in the late fall after it has gone dormant, and remove gradually in the spring.