‘Limelight’ Hydrangea A panicle type hydrangea (Hydrangea paniculata), ‘Limelight’ is a shrub that gives and gives. The flower clusters vary from 8 to 12 inches long and open chartreuse, then fade to pink shades. The color lingers well into fall. A tough plant, ‘Limelight’ is hardy in Zones 3 to 8. Panicle hydrangea trains well into a tree form.