Rhododendron catawbiense

Rhododendron catawbiense, commonly called Catawba rhododendron or mountain rosebay, is a large, rounded to spreading, multi-stemmed, broadleaf evergreen shrub that typically grows to 6-10’ (rarely to 20’) tall. It is native to the eastern U.S. from Maryland to Kentucky south to Alabama and Georgia, with concentrations in alpine woodlands, rocky slopes, and ridges in the Appalachian Mountains from Virginia to Georgia where it often forms dense thickets.  Its gray-brown bark develops fine scales with age.  This shrub is an important parent of a large number of frost-hardy hybrids. It will often become leggy when grown in unfavorable conditions. This plant blooms in late spring to early summer. Its enlarged floral buds are distinctive and present long before flowering. It is often used as a handsome, leathery, broadleaf evergreen, as a specimen plant, in mass planting, or occasionally in hedhes. 

This plant is winter hardy to USDA Zones 4-8 where it is best grown in acidic, humusy, organically rich, evenly moist, moisture-retentive but well-drained soils in part shade. It performs well with some morning sun but needs shady afternoon conditions. It will tolerate close to full shade. Prefers cool summer temperatures. Roots must never be allowed to dry out. Acidify soils prior to planting and thereafter as needed. Plant in locations protected from strong winter winds. Do not site plants within or near the drip line of trees in the walnut family (most rhododendrons are sensitive to toxic juglones produced by roots of walnuts, butternuts, pecans and hickories). Good soil drainage is essential (doesn’t like “wet feet”). Poor drainage inevitably leads to root rot, therefore raised beds/plantings should be considered in areas with heavy clay soils. Shallow, fibrous root systems (do not cultivate around plants) will benefit greatly from a mulch (e.g., wood chips, bark or pine needles) to help retain moisture and stabilize soil temperatures.

HIGHLY TOXIC MAY BE FATAL IF EATEN!

Fire Risk: This plant has a high flammability rating and should not be planted within the defensible space of your home. Select plants with a low flammability rating for the sites nearest your home. 

Insects, Diseases, and Other Plant Problems:  Rhododendrons are susceptible to insect and disease problems.  Insect problems include aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips, and whitefly.  Diseases include canker, crown rot, root rot, leaf spot, rust, and powdery mildew.  Full sun can scorch the leaves and the roots rot if the soil does not drain well.   A healthy plant in the right place with proper maintenance should have few problems. This plant is frequently damaged by deer.

Quick ID Hints:

• Long, leathery leaves, in tiers, congested at branch tips
• Large,5-lobed bell-shaped flowers with maculations
• Terminal clusters of flowers in raceme
• Evergreen shrub, tiered, sympodial growth
• Juvenile twigs yellowish

More information on Rhododendron.