If you can imagine snowflakes 12 inches across, you will have a sense of the extraordinary blossoms of the Annabelle hydrangea (Hydrangea arborescens “Annabelle”). This smooth hydrangea cultivar offers enormous, pure-white flower clusters that fill the bush from June through early fall; the flowers develop on strong stalks that rise up to 6 feet high. Do not try to squeeze verdant Annabelle hydrangea to your small corner; the cultivar demands plenty of room to flaunt its generous beauty. This organic cultivar thrives in U.S. Department of Agriculture plant hardiness zones 4 though 9 and must be pruned, in the end, in the fall.
Prune Annabelle hydrangea lightly just after its flowers fade in early fall. Use garden clippers to remove faded flowers as well as several inches of development in the tip of each branch. This cultivar occasionally supplies another flush of flowers following fall pruning.
Prune out damaged wood in the fall just after the leaves fall. Remove dead and broken branches by cutting at least 6 inches into healthy wood. Trim out crossing branches to protect against rubbing wounds. This is all of the pruning that is absolutely necessary for the plant.
Prune to rekindle the hydrangea, if needed, during fall dormancy when the bare branches are exposed. Annabelle blooms on new wood so dormant pruning does not reduce blossoms. Remove a few of the earliest stalks at ground level. Continue removing the earliest wood until you’ve taken out one-third of the plant.