The large orbs of pink, blue or white flowers make the hydrangea shrub stand out in the summer landscape. These deciduous plants go dormant in winter, but they must be cared for properly to prevent cold damage that can inhibit flower formation the following year. The type of winter care necessary depends on the variety of hydrangea you are growing. While all hydrangea offer some cold hardiness, some varieties are easier to overwinter than others.
Prune hills-of-snow and oakleaf hydrangea varieties in fall once they finish blooming but before the first frost. Cut hills-of-snow back to a 1- to 3-foot height each fall. Prune out deadwood from oakleaf hydrangea and cut back the oldest branches by up to 1/3 their length to encourage new growth the following spring.
Tie florist's hydrangea, also called hortensia, shoots together with gardening twine in early winter after the first frost. Cover the plant in burlap to protect it from winter chill and wind.
Spread a 6-inch layer of winter mulch, such as leaves or straw, around the base of the plants. Cover the crown of the hydrangea to protect it from winter temperature fluctuations.
Prune all hydrangea varieties in late winter or early spring before new growth begins. Cut out dead and damaged wood and cut back remaining branches to maintain the desired shape and size of the shrub.
If cold winter wind is a problem in your area, make a chicken wire cage around the hydrangea and fill it with leaf mulch. This protects the plant from the drying wind.