First from the image you sent it looks like a Pee Gee hydrangea. This is good because over time the trunk will thicken up and the tree will become stronger. (I have one that is 30 years old but it took about 7 years to become as strong as a tree.) Rather than using ties on the bark, make a corral around the trunk with four rebar stakes sticking at least five feet out of the ground. Next use soft twine that goes from stake to stake trapping the trunk inside the square corral but still allowing it to move slightly when the wind blows. When the trunk is allowed to move this causes more stabilizing roots to form so the tree grows stronger. If it continues to list to one side,  use a "Y" shaped branch to prop it upright by pushing it straight and propping with the branch. The branch should be pushing from the side where the tree is leaning towards. In a few years  your tree will be trained to stand upright. Keep growing, Marianne Binetti