Posted: 31/07/2016 at 09:34
You can move perennials if you lift up all the earth and roots around them and water well. A poster here, Verdun, has had success with it, so did my daughter when she moved house.
I don't know about the hydrangea, but if it's a question of it will die anyway because of the builders then it's worth giving it a go, taking as much root as you can. They dig up mature plants, even trees, for the Chelsea Flower Show.