I have potted three hydrangeas, they seemed to be doing well, but I notice that one of them (shrub) has flowers that look that the bloom is spent. Do I dead-head them the same as you do with roses? I had planned to bring them into the garage over winter and plant in ground in the spring. The pot has plenty of soil in it, and the pot in big enough to accomodate the shrub. Please and thank you. I am zone 6.