Azalea

Rhododendron (rho-doh-DEN-dron)

Family: Ericaceae Native Shrub (3-15 ft)

Azaleas and rhododendrons are woody, evergreen or deciduous, rounded shrubs in the Ericaceae blueberry family (Ericaceae). They are native to North America, Europe and Asia, and there are many cultivars and varieties. Some species are native to North Carolina. The genus name is compounded from the Greek words rhodo , which means “rose,” and dendron , meaning “tree.” These plants prefer moist, well-drained, acidic soils in dappled shade and protection from afternoon sun, which can scorch the leaves. They do not tolerate dense clay, so amend clay soil with organic material. The roots may rot if the soil does not drain well. Plant the root ball high in the soil to help with drainage issues. Avoid overwatering and over-fertilizing. Pruning, if desired, may be done after flowering. Per the American Rhododendron Society, "All azaleas are rhododendrons, but not all rhododendrons are azaleas." Here are some general characteristics to differentiate the two: Quick ID Hints for Azaleas: Bloom in April Tubular or funnel-shaped flowers One flower per stem but the shrub has many stems that make it look like it is covered in blooms 5 stamens Multiple bloom colors including white, cream, pink, red, lavender, purple, orange, and yellow Foliage elliptical to obovate, thin, small, entire margins, thick pubescence, cluster at the tips of the branch, buds are smaller Most are deciduous but there are many evergreens Quick ID Hints for Rhododendrons: Bloom later in the spring Bell-shaped flowers Blooms grow in clusters at the end of the branch 10 stamens Blooms are typically white, pink, purple, red, and rarely yellow Leaves are green elliptic, entire margins, thick, leathery, glossy, undersides may be scaly or have small dots Evergreen Azaleas and rhododendrons typically grow 6 to 10 feet tall and 5 to 8 feet wide. They are ideal for Asian, pollinator, butterfly, cottage, English formal, or winter gardens. They are at home as understory shrubs planted in groups in woodland or naturalized areas, or as specimens where the flowers will attract hummingbirds and the specialized bee Andrena cornelli . Some azaleas are offered as florist plants. Insects, Diseases, and Other Plant Problems: Insect problems include aphids, borers, lace bugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips, and whitefly. Diseases include canker, crown rot, root rot, leaf spot, rust, and powdery mildew. This plant is frequently damaged by deer. Many cultivars are susceptible to phytophthora root rot, which leads to leaf loss, reduced vigor, branch dieback, and wilting. Implement good cultural practices first, as described above. However, if you have a site with a history of this disease, consider planting root rot-resistant alternative species. See suggestions in the sidebar to the left or see this video created by Charlotte Glen as part of the Plants, Pests, and Pathogens series. The Clemson Cooperative Extension Home and Garden Information Center has a factsheet on common diseases of rhododendron. VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers," a plant identification course developed in partnership with Longwood Gardens.

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 74 attributes.