There are several reasons why hydrangeas fail to bloom.  Most often the cause is pruning too late in the spring and cutting off the flower buds or the second year growth. Many of the hydrangea varieties flower on two year old wood so annual pruning removes the flowering branches. An exception is the "Endlesss Summer" hydrangeas that bloom on both old and new wood. The other most common cause is a spring frost that freezes and destroys the newly formed flower buds. Try providing a wind break for the shrubs if you live in a cold winter area or cover them with a sheet if a late spring frost is predicted. The mountain hydrangeas are a variety that can handle colder weather. Hydrangeas also need at least half a day of sun preferably in the morning to bloom best. Too little water in the summer can also stress them out and cause less flower production. Hydrangeas flower best when they are never pruned.  To keep your hydrangeas blue and well fed you should apply the new Osmocote Hydrangea food in the spring.  Just follow the instructions on the package and work the fertilizer very lightly into the soil around your plants. I am thinking you'll have a better display of blooms this summer and if you don't over do it on the pruning, protect the plants from cold winds, water in the summer if needed and make sure the shrubs are getting some sun - you will enjoy a flower filled future.  Keep growing, Marianne Binetti