Rhododendron maximum aka American Rhododendron

Rhododendron maximum is an evergreen shrub in the heath family. Gardeners call it rosebay rhododendron or great laurel. It grows in eastern North America, from Ontario and Nova Scotia southward. Its range reaches Ohio, Alabama, and Georgia. Many plants grow in the southern Appalachian Mountains. There, dense stands can fill the space beneath forest trees.

In gardens, it grows 5–15 feet [1.5–4.6 metres] tall. Some accounts give heights of 20 feet [6.1 metres]. Wild plants can reach 30–40 feet [9.1–12.2 metres]. Its garden spread reaches about 12 feet [3.7 metres]. Several stems form a loose, upright shrub with spreading branches. Young bark is smooth and pale brown; older bark forms scales. Thick, dark green leaves have smooth edges and rusty hairs beneath. They measure 0.33–0.67 feet [0.10–0.20 metres] long. The leaves stay green rather than taking on fall color.

Flowers open later than those of many large-leaved rhododendrons. Bloom falls in June and July, sometimes lasting into August. Clusters hold up to 25 pink, white, or lilac-pink flowers. Green or orange spots mark the petals. New shoots can hide some of the blooms. Bees, butterflies, and hummingbirds visit them for nectar. Long seed capsules appear in September and October. Each ripe capsule splits and releases many seeds.

Give this shrub partial or dappled shade and a cool site. It also tolerates deep shade, but afternoon sun can scorch leaves. It needs acid soil rich in humus, with good drainage. Keep roots moist without leaving them in soggy ground. Mulch helps its shallow roots hold moisture and stay cool. Avoid digging around the roots, and shelter plants from strong winds. It suits USDA zones 3–7 and has an RHS rating of H7. Little pruning is needed. Use it in woodland groups, shady borders, or screens. Its foliage gives winter cover and year-round garden structure.

Lace bugs, aphids, scale insects, and whiteflies may attack plants. Diseases include root rot, canker, leaf spot, and powdery mildew. Poor drainage raises the risk of root rot. Deer often damage plants, while exposed sites can cause winter burn. High soil pH can make leaves turn yellow. The plant is harmful to people and pets when eaten. No edible uses are known. Reports of folk medicine do not remove the poisoning risk. Its hard wood has served for tool handles and engraving.