Azalea (Rhododendron species): Hardiness zone 5-8, depending on cultivar; evergreen and deciduous; two to 12 feet tall and width about one and a half the height; rounded shrub; dark green leaves; fabulous intensity and variety of flower color that covers the entire plant; moderate growth rate; will not tolerate dry, windy sites, needs good moisture, acid soil and good drainage.
Burkwood Viburnum (Viburnum x burkwoodii): Hardiness zone 5-8; deciduous; shade to early morning sun; eight to 10 feet tall and similar width; upright, rounded, open shrub; oblong, dark green leaves turn wine-red some falls; pink buds open to reveal white flowers in April; slow-moderate growth rate; amend soil with organic matter before planting; “Mohawk” highly rated cultivar.
Koreanspice Viburnum (Viburnum carlesii): Hardiness zone 5-8; deciduous; shade to early morning sun; four to five feet tall and four to eight feet wide; rounded, dense shrub; medium-sized, rounded, dull, dark green leaves sporadically turn reddish in the fall; pink to red buds open to reveal white, very fragrant blossoms in and May; slow growth rate. “Aurora,” “Carlotta” and “Cayuga” are newer cultivars.
European Cranberry Viburnum (Viburnum opulus): Hardiness zone 3-8; deciduous; shade to part sun; eight to12 feet tall and 10-15 feet wide; upright, spreading, multi-stem habit; medium-sized, lobed, dark green leaves sporadically turn yellow-red to reddish purple in the fall; reveal white, highly fragrant blossoms in May; fast grower.
Ray Ridlen is an educator for the Oklahoma County Extension Service. His column addresses frequently asked horticulture questions. For more information, call 713-1125.