Are you pruning off the growth that was going to flower? Hydrangeas flower on old wood. Try feeding, watering if necessary and otherwise leaving it alone.

The idea generally is to leave the dead flower heads on through the winter to protect the emerging shoots and flower buds from frost. When you can see healthy new shoots and all danger of frost has passed, then you can prune off the old flower heads and it should continue to bloom beautifully. :o)

Pruning absolutely as Nariz says - you only remove dead flowerheads and dead stems, usually in April when the new growth starts showing, though where you live ,it might be later.
Other cause of non flowering is dryness at the roots, usually caused by being planted too close to the root system of a large tree or shrub.