Prune immediately after blooming and not before as this will affect next years blooms. Remove only dead stems in the spring. Mulch with bark, straw, leaves or pine needles in the fall. If possible, make a cage out of chicken wire or snow fencing and loosely cover the entire plant with leaves. The use of maple leaves is not recommended.1
Try to plant in a location that enjoys partial sun and remember to water often. Hortensia is generally regarded as a half hardy plant, so it will require protection in frosts and low temperatures.The term macrophylla means large or long-leave.
1 www.almanac.com/plant/hydrangea