Your climate, Bonnie. From your photos these appear to be hydrangea macrophylla that do bloom on wood grown the previous year. In your climate, those stems are being winter killed. You may need to winter protect to achieve flowers, or replace with something like h. arborescens Annabelle that blooms on new wood.

Your new growth certainly looks bright and healthy...

There are several thread on winter protection if you search using the box at the top of the Hydrangea forum thread and choose the option of looking only in the Hydrangea forum.

Other options that you have in addition to winter protecting:

(1) switch these shrubs for re-blooming hydrangeas. The stems of the re-blooming hydrangeas will also dry out and die (unless you winter protect) but the new stems that grow from the crown should produce blooms (later) in late June or July.Just remember not to prune between leaf out time and blooming time.

(2) Another option is to switch these for hydrangeas that are hardy to Zone 5. These three are hardy: oakleaf hydrangeas, Annabelle-like hydrangeas and paniculatas.

Of those, oakleaf hydrangeas are hardy to Zone 5 but bloom on old wood so there is some change is this problem cropping with them, although their stems are hardier and this happens much less than with mopheads. They have gorgeous fall foliage too.

The other two produce blooms from new wood and as the result of that, they bloom more reliably for your zone... with no winter protection whatsoever. But, yeah, you do not get those nice blues, purples, etc.

You need to watch your Spring nightly low temperatures. If there is green at the bases FIRST and THEN if there is ANY nightly low below about 27 degrees Fahrenheit, you will be in danger of losing any and all stems because the plant has broken dormancy and the buds are vulnerable. Very few winter or other protection methods can save the plants from a harsh spring freeze.

Thanks to everyone. I think I will replace them. Along with other landscape changes I am aiming for a more fuss-free garden. Last year I already planted 3 paniculata's which made it through the winter and spring fine. Thanks again.