Those are all different kinds of hydrangea, and each have different winter hardiness. Rated in winter hardiness from best to worst they are (obviously) 2-3-1. Winters of 2014 and 15 were harsher than normal.

#3 looks like a Nikko Blue which will bloom sporadically after a harsh winter. #2 is a Preziosa which takes harsh winters rather well.

Those three all set flower buds on previous year's growth (a.k.a. Old wood). They can only withstand winter lows from about 0 (plant #1) to -20 (#2) Fahrenheit. Prolonged lows about -10 or below will take their toll on the stems, and in many cases, kill them back to the ground.

So whatever the circumstance, do NOT do any trimming or pruning after about right now, each year, or you will risk cutting off next year's flowers. Otherwise, throw a large pile of leaves over #1 come November (to insulate it from winter conditions) and it will be much more likely to bloom.

After about Memorial Day, you can cut back any brown or grey sticks that don't put out new growth. Until such time, the plants might look a little unsightly as their growth takes til almost early June to take off in zone 6.

After these last two very bad winters, I too "vote" for winter problems although sometimes deer may eat all/most of the flower buds on the top and leave some at the bottom alone. Deer would probably eat more blooms from #3 at the bottom and leave sporadic ones here and there though (or eat all if really hungry).

But the reason I lean with winter too as the cause is I have one like #1 this year and one like #3 (although mine had just two blooms at the bottom). I also have one similar to #2 near the others and other unaffected ones that are in protected locations.

Winter protect this year to see if that helps or use hardier hydrangeas that bloom on new wood (paniculatas and arborescens); they form invisible flower buds in mid-to-late Spring and the blooms open later like in July... but they do not have colored blooms like the mopheads).