Why are my hydrangeas not blooming?
These plants are 2-4 years old.
Certified GKH Gardening Expert
That is a common complaint about hydrangeas. If you buy any new ones, get one that grows on new wood like the pannicle varieties, so winter weather or pruning won't affect it.
Usually if hydrangeas don't bloom, it's because the buds were cut off during pruning or because of winter kill. Here is more information: