We bought a house with 8 - 10 foot tall hydrangea, they bloomed early spring and that was it. Is this normal and do I need to trim back
Hydrangea, depending on the variety can bloom from spring into midsummer. The flowers will fade as they age and will generally dry on the plants. They can be left on the plants for interest all winter long.
Here are some links that will refresh you on the care requirements.