This form of the eastern US native smooth hydrangea lives up to its trade name of Incrediball with huge mophead flower clusters in late spring to early summer. The 10″ flower clusters open lime green before quickly turning white and are held erect on very sturdy stems. Unlike most of the Asian hydrangeas, smooth hydrangeas flower on new growth and so can be cut to the ground each winter. They make great garden plants from the deep south to very cold climates. Grow in part shade or full sun with supplemental summer irrigation.