My 2-3 yr old hydrangea in cold weather, cut back/how much?

Put a potted hydrangea in my flowerbed about 2 maybe 3 years ago. It's taken awhile to grow to this height. In the spring,summer and fall it's pretty and green but has never produced flowers. See photo....this is how it looks in the winter. Need advice on winter maintenance... Cut back, how much? Thanks guys
q my 2 3 yr old hydrangea in cold weather cut back how much
  7 answers