There are methods using bamboo stakes and twine that form a criss-cross pattern around a row of hydrangeas, or a star shape for individual ones. But for the life of me I can't find one YouTube right now. I'll keep looking and post one when I find it again. Those are easier to set up before they get too tall, but can still be done now.
Another thing some do is to place a tomato cage in the center of the plant in spring. Then as it grows out, the cage is invisible and always supporting the majority of the plant.
Here's one that shows the method for a larger row of hydrangeas:
https://www.youtube.com/watch?...
And found the other from going through my history for the star-shaped pattern:
https://www.youtube.com/watch?...
