A couple of years ago I received a potted hydrangea as a gift. I planted it outdoors in my garden in partial sun. Ever since then, I have not had any blooms.
Your hydrangea is probably the type that blooms on old wood. Pruning the plants back to the ground or winter dieback to the soil surface eliminates the flowering wood for the following season. Start by leaving the plants stand for winter. You may want to increase your chance of success by mulching the plants. Cover the plants, after the ground freezes, with straw or evergreen branches. In spring, prune back only the dead tips and lightly shape. The new growth that sprouts from the older stems should flower. And be sure not to over fertilize. Too much nitrogen will give you beautiful leaves but no flowers.