Hi, Dina. We have several hydrangeas around our house - they can grow quite large, 5-6 feet tall and wide. I can't quite envision putting them in a planter under a patio - to me, a patio is on the ground. Do you mean a deck, raised above the ground? If there's enough vertical space under it, I guess they would do all right. They grow naturally in the woods under large, shady trees, so that's the kind of environment they do best in. HTH.
The trouble with eating Italian food is that five or six days later you're hungry again. ~ George Miller