Often confused for a hydrangea, Chinese snowball viburnum (Viburnum macrocephalum) is a showstopper in the front yard. "In late spring, large white flowers cover the plants so long as they are not in too much shade," says Roethling. "Some re-flowering can occur in fall. The flowers come out green and, when fully open, brighten to a giant white, snowball-like inflorescence." This tree variety does well with pruning should it begin to outgrow its space.