Annabelle Hydrangea is a popular shrub to use as a border or for groupings. It is a large-flowered cultivar of the native Smooth Hydrangea. Large, dome-shaped heads of sterile flowers bloom in July and are long-lasting. Spent flower heads are a good addition for winter interest. Deep green leaves turn yellow in the fall. Annabelle Hydrangea produces more flowers in full sun, but needs adequate moisture during dry, hot weather.