Hydrangea shrubs vary significantly between varieties, with different blooming habits and different needs. Before pruning a hydrangea, know what hydrangea variety you are growing so you do not inadvertently prune away future blooms. Some hydrangeas bloom on new wood, such as Panicle and Smooth hydrangeas, and some hydrangeas bloom on old wood, such as Oakleaf and Bigleaf hydrangeas. The only care hydrangeas require after the flowers wilt is to prune away dead wood on the varieties that bloom on old wood.
Examine hydrangea shrubs that blossom on old wood immediately after the blossoms wilt. Look for dead wood that exists on the shrubs and trim away approximately one-third of the oldest stems by cutting them off just above the base of the shrub with the pruning shears. Discard these branches.
Shape the hydrangea shrub if you wish to control the growth. Look at the tips of the stems and find a point with two healthy buds. Clip the stems just above this point with the pruning shears.
Remove stems from the interior of the shrub if you find congested areas where stems are crossing each other and rubbing. Remove these stems back to the point where they intersect with larger stems with the pruning shears.