Catawba rhododendron is a large-leaved, evergreen shrub reaching 6 to 10 feet high with large, lilac-purple flowers borne in clusters (trusses) in mid to late spring. Excellent for shade gardens or in a sheltered site. Requires well-drained, acidic soils. Native to the southeastern United States.
Native geographic location and habitat:
Catawba rhododendron is native to the eastern United States, the Allegheny mountains, West Virginia, Georgia, and Alabama.
Bark color and texture:
New stem growth is a yellowish-green which becomes brown with age.
Leaf or needle arrangement, size, shape, and texture:
Leaves are elliptical, alternate, 3 to 6 inches long and 2 inches wide, dark green in color, and leathery in texture.
Flower arrangement, shape, and size:
Large, 5 to 6 inch clusters (trusses) of individual lilac-purple flowers emerge in late May to early June. The corolla has yellow to brown markings inside.
Fruit, cone, nut, and seed descriptions:
The seed is a five-valved dehiscent capsule.
Grows best in part shade in a protected site. Morning sun and afternoon shade is best in hot summers. Prefers organic-rich, acidic, well-drained soils. Rhododendron can show chlorotic symptoms in high pH soils. Amend soil at time of planting. Good drainage is essential. Roots are shallow and fibrous, so avoid wet clay soils which can cause root rot. Plants benefit from a layer of mulch to retain moisture and moderate soil temperature fluctuations. This shrub flowers on older wood and is hardy to -25°F. Deadheading is not necessary but flowers can be snipped off carefully after blooming. To protect plants from winter winds, wrap a cylinder of fencing around the plant and backfill with leaves once the ground freezes.
List of pests, diseases, and tolerances:
Black vine weevils, borers, lace bugs, aphids, scale insects, thrips, mites, canker, crown rot, root rots, powdery mildew, and rust. Rhododendrons are susceptible to black walnut toxicity and should not be planted near walnut trees.
All cultivars are similar to species but vary in flower color.
White Catawba rhododendron (Rhododendron catawbiense f. album):
This cultivar has pure white flower trusses with greenish spotting and excellent hardiness to -25° F.
English Rose Catawba rhododenron (Rhododendron catawbiense ‘English Roseum’):
Light rose trusses and hardy to -25° F.
Nova Zembla Catawba rhododendron (Rhododendron catawbiense ‘Nova Zembla’):
This cultivar has red to lavender-red trusses and is hardy to -25° F.
Roseum Elegans Catawba rhododendron (Rhododendron catawbiense ‘Roseum Elegans’):
An old-fashioned cultivar with lavender-pink trusses and hardy to -25° F.