This still remains a very popular question when spending time in the garden with my customers.
Here is a picture of my Endless Summer hydrangea in the beginning of June:
Resist the temptation… no matter how great to take off the stems that are sticking out of the plant.
The old wood is where the 1st blooms will come from. The plant will slowly fill out like this:
Hard to tell from the picture but I am already getting buds on the plant and flowers should start to bloom by the end of June.
Hope that helps everyone who wants to extend their hydrangeas blooming season!