After living in this house for five years, three of my four hydrangea plants have bloomed (one or two blooms per plant). I've searched for the variety online, but there are so many, I cannot pin down what they are. Clues: old wood produces buds in fall (which have been either freezing over winter or eaten by deer). However, this year's blooms are all on new shoots. If you know what they are, I may be able to search from some ideas on how to get more blooms or where to move them this fall to improve their productivity. Thanks! P.S. Zone 4A.

Since you're in zone 4 and it blooms unreliably, and on old or new wood, look up Endless Summer hydrangeas. Endless Summer is a trade designation and not a cultivar name but it gives you a starting point. I don't think any of the other blue ones would survive at all in zone 4.