The roots need time to extend into the surrounding soil. With woody plants, that requires at least two years of regular supplemental irrigation.

For now, be certain the original rootballs remain adequately moist because that's where the roots are.

Hello,
I have the same problem with my Hydrangeas. I call them whimpy now. The place I bought them at told me to turn the hose on them every three days and let it run for 20". They love the water! Your not alone!
:-)

I have this problem also. My hydrangeas are very old and established and are very heavy at the tip of the plant where the flower grows. Not only do they wilt but they also hang to the ground. Is it possible they need pruning all the way back to strengthen the branch? I usually only cut back beyond the flower once it dies in the winter. Should I be cutting it back further?

I PLANT MINE AFTER I DIG THE HOLE I MIX A HUGGIE DIAPER NOT THE PLASTIC PART AND THE POTTING SOIL TOGETHER THIS MIXTURE CAN REALLY HOLD SOME WATER AND WE ALL KNOW THE HYDRANGAS LOVE THE WATER ALSO I HAVE MINE IN MOSTLY DAPPLED SUN TOO MUCH SUN WILL KILL A HYDRANGEA OR AT LEAST IT DOES MINE ALSO I MAKE THE HOLE LARGE SO IT CAN SPREAD AND NOT BE CRAMPED FOR ROOT GROWTH..