I have a massive burning bush in my back yard, and several overgrown rhododendrons. I'm planning on cutting them back substantially. I'm in MA so we're right at the peak of summer heat right now. When would be the best time to cut them back? Someone told me it is best to wait until late November when the temperatures have dropped and the plants have hardened up for the winter but I wasn't sure if this was good advice or just completely wrong.