Culture
Best grown in acidic, humusy, organically rich, medium moisture, moisture-retentive but well-drained soils in part shade. Prefers a sun dappled or high open shade. Morning sun with afternoon shade is also acceptable. Foliage may scorch in full sun. Plant in a location protected from strong winds. Do not site plants within or near the dripline of trees in the walnut family (most rhododendrons are sensitive to toxic juglones produced by roots of walnuts, butternuts, pecans and hickories). Good soil drainage is essential (plants do not like “wet feet”). Poor drainage inevitably leads to root rot, therefore raised beds/plantings should be considered in heavy clay soils such as those present in much of the St. Louis area. Shallow, fibrous root systems (do not cultivate around plants) will benefit greatly from a mulch (e.g., wood chips, bark or pine needles) to help retain moisture and stabilize soil temperatures. Roots must never be allowed to dry out. Acidify soils as needed (plants generally like soil pH in the range of 5.0 to 5.5). Add sulfur or iron sulfate to soils to lower the pH. Add limestone or lime to soils to raise the pH. Clip off spent flower clusters immediately after bloom as practicable.
Noteworthy Characteristics
Rhododendron myrtifolium is a compact broadleaf evergreen that is primarily native to the Carpathian and Balkan mountains. It is a creeping shrub that typically grows to only 2' tall but spreads to 3' or more wide. Small, evergreen, shiny dark green leaves (to 1" long) are elliptic to oblanceolate. Leaves turn bronze red in winter. Leaves are scaleless above, but have dense scales (lepidote) on leaf undersides. Tubular, rose to purple-pink flowers in clusters of 3-7 bloom in mid to late season (late April to May in St. Louis).
Genus name comes from the Greek words rhodo meaning rose and dendron meaning tree. Transferred from the Greek name for Nerium oleander.
Specific epithet is in reference to the myrtle-like leaves of this rhododendron.
Problems
Rhododendrons are susceptible to many insect and disease problems, including but not limited to canker, crown rot, root rot, leaf spot, rust, powdery mildew, aphids, borers, lacebugs, leafhoppers, mealybugs, mites, nematodes, scale, thrips and whitefly. A healthy plant in the proper environment with proper care should have limited problems, however.
Uses
Sun-dappled or afternoon-shaded areas of rock gardens, small gardens, foundations woodland gardens or mixed borders. Attractive evergreen foliage and compact size make this an excellent selection for small garden areas.