Rich reddish-purple flowers cover this low mound in spring, and the foliage carries a burgundy cast that deepens through cold weather. Rhododendron Midnight Ruby grows 2 to 3 feet tall and wide in part shade, hardy from Zone 4 through Zone 8.
The leaves are small and dark, and the compact size suits a foundation bed or a container.
The small-leaved rhododendrons, sometimes called lepidotes, differ from the big-leaf types in more than size. They flower earlier, take more sun, handle cold better, and the foliage turns mahogany or plum through winter instead of staying green. The leaves are aromatic, releasing a spicy scent when brushed. In colder gardens they behave as semi-evergreens, dropping a share of the older interior leaves over winter while holding the newer growth at the branch tips. That thinning is normal and the plant refoliates in spring.
Zone 4 hardiness puts it further north than most. Acidic soil is necessary, roughly pH 4.5 to 6.0, with good drainage and steady moisture. Mulch the shallow roots.