My hydrangea plants are at least 12 years old and they have always produced beautiful blue flowers. 4 yrs. ago the larger one on the east side of the house was filled with flowers and the smaller one on the west side of the house only had a couple of flowers, but since then we only get 1 or 2 flowers on the east plant and none on the west plant. I wait until spring to trim the dead wood. I was told to trim them down to the ground and start over, but I hesitate to do that because I would hate to lose the plants. Can you help me?
Unfortunately, what you have described isn't unusual. Following is an somewhat dated but excellent discussion of problems associated with growing Endless Summer hydrangea. (We presume you are referring to this variety.)
Although information in the article is addressed to growers in the Chicago area, most of it also applies to Minnesota.