They all leaf out at different times (when they are good and ready). The ones that were planted last year are sometimes notorious for being late. If they made it thru winter, they should leaf out by the end of the month at the latest. So just keep giving them TLC like if they had already awakened. If you get nothing by Month end, the odds are not their favor. Were they all planted last year?

Black-stemmed hydrangeas like Zebra, Nigra, Midnight Duchess and the Abracadabra Series typically bloom on flower buds developed during July-August of the prev year so, to bloom reliably, they will need winter protection.

If Zebra generates new stems this year, it will produce flower buds at the end of the stems in July-August 2016 for Spring 2017. To make sure the stems make it thru Winter 2017, winter protect it in the Fall.

They were all planted last year. There are leaves at the base of the Zebra hydrangea, but none on the cityline hydrangeas. I'll protect the Zebra this fall for sure. Thank you.

Sometimes heavy frost or freeze damage can affect the crown of the plants and they'll barely put out anything in certain years. When this happens I sometimes am forced to rehab the plant in a pot for a year or two before I put it back in the ground. This serves as a great excuse to buy something new and full looking to drop into the hole where the rehabbing plant was removed from. :)

[If you pot these and don't see any growth by mid-summer, they're probably toast]

Great idea springwood_gardens, I'll wait another two-three weeks and if nothing happens, I'll pot them and hope for the best.