Rhododendron kaempferi

Torch azalea is a woody, evergreen to semi-evergreen shrub in the Ericaceae (blueberry) family. Found growing in the mountainous regions and grassy hills of Japan.  The genus name derives from the Greek words rhodo, which means rose, and dendron, meaning tree.  

This erect multistemed shrub has an dense rounded canopy and can grow from 4 to 10 feet tall and 5 to 6 feet wide in about 10 years. Plant in partial to dappled shade with up to 4 hours of sun.  While plants may flower better with more sun, it becomes difficult to maintain their water needs and they can burn.  They need moist well-drained rich acidic soils, avoiding poorly drained soils.  If this is not possible consider planting in a raised bed.  Torch azalea will need some protection from cold so plant it in a sheltered location in the landscape.  Propagate this plant through stem cuttings.

The leaves are evergreen in mild climates and semi-evergreen in areas with cold winters and they provide attractive fall color.  Showy salmon pink to rose red flowers appear late spring to early summer and are one of the few shade flowering evergreen shrubs. 

Low maintenance and easy to grow. This shrub is less demanding than Kurume azaleas (Rhododendron ponticum).  It is the parent plant to many evergreen azaleas.

It works well in a woodland, naturalized area, or Asian garden, planted in a container, window box or near a shaded patio or walkway where the blooms can be enjoyed.  It can be grown as a houseplant.  This plant is often browsed by deer and rabbits, especially new growth, so may need protection. 

Insects, Diseases, and Other Plant Problems:  Rhododendrons are susceptible to insect and disease 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.  Full sun can scorch the leaves and the roots rot if the soil does not drain well.   A healthy plant in the right place with proper maintenance should have few problems. This plant is frequently damaged by deer. 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.