White Diamonds® panicle hydrangea (Hydrangea paniculata 'Hypmad I') was developed by Michael Dirr, Ph.D., at the University of Georgia, and it features pure white flowers for eight weeks at the end of summer and beginning of fall. This is a more compact panicle hydrangea cultivar that matures to between 4 and 6 feet in height and width. Plant White Diamonds® in a sunny location and water during dry spells. As the flower bracts age in the fall, they turn burgundy pink.