Do you try to maintain constant soil moisture on all during the summer and winter as much as much as is practical? Flower buds can be killed by a sudden lack of water.

What varieties are these? Some like the Endless Summer Hydrangea cause a lot of bloomage problems posts in the Forum.

Did the hydrangeas on the sides not have any flower buds this Spring? Lack of buds suggests that something killed them, usually winter or moisture problems. Any competing plants or trees around them? Any juglone-producing trees (black walnut, butternut, etc)?

Luis