Impeditum Rhododendron Rhododendron impeditum

Dwarf purple rhododendron is a woody, compact, slow-growing, broadleaf evergreen shrub or groundcover in the Ericaceae (blueberry) family. It is native to China. This rhododendron grows to a height of 1 foot and width of 1 to 2 feet. The genus name derives from the Greek words rhodo, which means rose, and dendron, meaning tree.

This plant prefers moist, well-drained, acidic soil in dappled shade and protection from afternoon sun which can scorch the leaves. It does not tolerate dense clay, so if you have clay soil, amend with organic material. The roots may rot if soil does not drain well. Plant the root ball high in the soil to help with drainage issues. Avoid overwatering and over-fertilizing.  

Dwarf purple rhododendron blooms in the spring with spectacular purple flowers that completely cover the plant. It has fragrant, tiny, leathery, gray-green leaves that provide year-round interest. 

Plant it in small groups in border fronts, rock, or woodland gardens. Plant it at about 15 inches apart and the plants will grow together to form a dense groundcover. This plant is often chosen for bonsai. It is resistant to damage by deer.

Prune rhododendrons and azaleas after they bloom to preserve the current season's bloom, and allow time for the plant to produce flower buds for next year's bloom.  Rhododendrons and azaleas set next year's flower buds by mid to late summer. 

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.  

While rhododendrons remain very popular for landscape use, many cultivars are susceptible to Phytophthora root rot—this leads to leaf loss, reduced vigor, branch dieback, and wilting. Implement good cultural practices first, such as improving drainage with organic matter or berms and avoiding overwatering or overfertilization. For suitable alternatives, see this video created by Charlotte Glen as part of the Plants, Pests, and Pathogens series.

VIDEO Created by Elizabeth Meyer for "Trees, Shrubs and Conifers" a plant identification course offered in partnership with Longwood Gardens.

More information on Rhododendron.