This is when the calls start on my Sunday morning radio show, "why isn't my hydrangea blooming," they ask.
Hydrangea macrophylla is the most popular variety, it's also known as a mophead hydrangea. If it's pruned improperly, it won't bloom. If the buds freeze, it won't bloom.
Most macrophylla plants put buds on during the late summer. If it's pruned before they get a chance to bloom, then the buds have been removed and therefore, no blossoms.
If the plant is out, unprotected in the landscape, cold weather can freeze the buds. I've started surrounding my plants with burlap. Now I've got lots of flowers.
There are other types of hydrangeas which are more reliable bloomers in our climate.
One of my favorites is the oak leaf hydrangea. It's not a one trick pony either, with four seasons of interest. First are beautiful conical white blooms which fade to pink. In the fall the leaves turn deep red and for the winter, the bark is exfoliating and bronze. It's a great plant.
The Annebelle hydrangea (Hydrangea arborescens) is a great old fashioned plant. I just wrote about a pink version.
Another way to get good blooms is to look for varieties which bloom on new and old wood like Endless Summer. If the buds freeze over the winter, new growth will make flowers.
Spend some time at a good nursery and find the plant which will give you years of satisfaction.