Question
I planted big leaf hydrengras three years ago, they were blooming when I planted them, and they bloomed the following year but have not bloomed again since.  What am I doing wrong?

Answer
Melinda,
Did you prune them in the fall? This is the biggest reason why Hydrangeas fail to bloom. Hydrangeas set up their flower buds on old wood in the late summer. If you are pruning them after early september, then you are cutting off the flower buds for next year.
There are no insects that would stop the plant from flowering.
There is a disease that affects the buds, but this is rare.
I hope this helped.
Good luck.
Ed Gulliksen