Experts and BHG readers answer.
Endless Summer hydrangea problem
There are a few simple things you can do to encourage your Hydrangea to bloom. In a northern climate like yours, Endless Summer Hydrangea needs to be in part sun. Six hours of morning sun followed by some light afternoon shade is ideal; too much shade all day will inhibit bloom production. Fertilize your Hydrangea once per year in spring with a slow-release granular fertilizer. Look for a formulation high in phosphorous; 10-30-10 or something similar. Finally, mulch your Hydrangea in winter to protect the tender buds that emerge in spring from a late freeze.