My two hydrangeas which were new last summer, haven't flowered this summer. Could they have been caught by a late frost?
Yes, a late frost will nip the bud. Also important is when you pruned them. Some hydrangeas bloom on old wood (bigleaf, aka macrophylla, and oakleaf hydrangea), some on same-year growth. If you have an old-wood cultivar, pruning those dead-looking stems will remove this year's blooms. Too much sun, particularly the hot afternoon sun, also seems to be a factor. If you don't know what type you have, go to a grower's website to view them. Here is White Flower Farm: http://www.whiteflowerfarm.com/all-hydrangeas