My hydrangea has green leaves and no blooms. Why?

Could be a few things! Do they get morning sun and afternoon shade? That's usually the ideal to promote blooming. Also, do you prune?

Yes, it gets morning sun and afternoon shade. Yes, I pruned. Should I not have?

Some varieties can be pruned and others need the old wood to produce the flowers. Depends on the variety.

It is also possible that you suffered a freeze after the buds set which will result in a beautiful bushy green plant and no blooms.

Sometimes mine gets so straggily, I cut to the ground and let it come again. They are a fantastic plant for piled snow....where it comes off the roof or the snowplow piles..the plant doesn't seem to suffer. Yes, most hydrangeas bloom on last years stalks.

Have you fertilized this year? Hydrangeas do especially well when fertilizers are effectively used in spring or early summer. I recommend using a granular, slow-release fertilizer with a high percentage of phosphorus (the middle number in the NPK ratio). Phosphorus is the element that encourages bloom production. Follow the package instructions when applying fertilizer and be sure not to use too much. Over-fertilizing can cause hydrangeas to grow big green leaves, but stunt bloom production. - See more at: http://www.endlesssummerblooms.com/design-and-grow/planting-and-care?gclid=Cj0KEQjwo-XIBRCOycL7hsuI_NoBEiQAuS6HtMvwlyF0SOGlkWbhsGsSMRP6Xf1jC52ZMpTkjQD9zBQaAj2h8P8HAQ#sthash.4CL3QEqm.dpuf

That happened to us, too. I think it was too hot and I didn't water it enough.