Winter care of hydrangeas
Hydrangeas are not overly keen on being pruned back hard as they tend not to recover quickly from aggressive pruning.
Ideally you need to leave any pruning until early spring just as the buds begin to shoot. The idea being that the existing growth on the hydrangeas provided protection overwinter providing some protection to the crown and roots of the plants in the harder winter weather.
In the spring start by removing the dead and damaged stems within the plants next remove up to a third of the stems length to contain the size of your hydrangeas and encourage new flowering shoots to form. Finally finish with the general feed such as growmore fertiliser just to ensure some strong spring and summer growth.