Flowering shrubs put on a colorful show in the park in spring and summer. Nine species of native shrubs in the rhododendron genus live in the park: rosebay (white) rhododendron, Catawba (purple) rhododendron, flame azalea, sweet azalea, Cumberland azalea, small-leaved azalea, pinxter-bush, pink azalea, and clammy azalea. Together they cover thousands of acres in the national park.
Although azalea are grouped in the rhododendron genus (members of the heath family), when most people consider rhododendron, they are thinking about either rosebay or Catawba.
Rosebay rhododendron is the most common rhododendron in the Smokies. It thrives around streams and in ravines at elevations below 5,000 feet. Rosebay’s big clumps of whitish flowers appear in June at the lower elevation and from July into August at the middle altitudes.
Not every rosebay rhododendron in the park blooms every year. “Big blooms,” when a higher percentage of the shrubs bear flowers occur every 2-4 years. No one yet has figured out when big blooms will happen, or why. Even during off years, however, many rosebays will bloom throughout the park, especially those along roadsides that receive more direct sunlight.
Catawba is the rhododendron of the Smokies’ high mountains. It is found only at elevations greater than 3,500 feet in the park, often alongside other rhododendrons as part of tree-less shrublands call heath balds.
Catawba’s leaves are thick, shiny, and evergreen, much like those of rosebay rhododendron. However, Catawba leaves are not as long and have a more rounded shape.
The beauty of Catawba rhododendron’s purple flowers is legendary. From a distance it appears as if rhododendron-covered ridges have been painted with a purple wash.
Catawba usually reaches its peak of bloom along the Newfound Gap Road in the first half of June. Along the highest peaks it flowers in late June. Good places to see it are: above the Chimney Tops Trailhead, Alum Cave Trail, the Blue Ridge Parkway, and Andrews Bald.
When pioneer botanist William Bartram discovered flame azaleas in 1791, he described the plant as “certainly the most gay and brilliant flowering shrub yet known.”
In the Smokies, flame azalea flower colors range from white to peach to orange, yellow, or red. Blooming time is April and May in the pine and oak forests at low to mid-elevation, but not until June or early July on the mountain tops. The famous displays on Gregory Bald bloom in mid to late June and on Andrews Bald in late June. Flame azalea can also be seen on Balsam Mountain Road.
Mountain Laurel (genus Kalmia) shows its white and pink flowers from early May through June on trails and roadways throughout the park.