I have 20 mophead hydrangea plants around the front of my seaside home. These plants are probably 20 years old and are blooming profusely. Lots of flowers but too many on one stem. There is old wood and new wood. I have tried to prune them properly but I always seem to miss the right time. I would like to make them more compact and have larger blooms on single stems. Right now, I have some stems supporting 6 blooms. They are too heavy and with all our fog and morning mist, they have lots of brown flowers on the tips and hang heavily to the ground. What can I do to tighten them up? I fertilize with Hollytone in the Spring and try to take out the older canes but it kills me to remove too many of them. Any suggestions are welcome. The flowers are pink and blue - some flowers are 2 toned. I would love deeper blue to purple coloring.