Best grown in humusy, organically rich, acidic, medium moisture, well-drained soils in full sun to part shade. In St. Louis, Japanese pieris doesn’t seem to perform well in most locations. Summer foliage decline and reduced vigor often result in weakened plants that may succumb to harsh winters. It grows best in locations sheltered from wind with part afternoon shade. Remove spent flowers immediately after bloom.
Japanese pieris is a slow-growing broadleaf evergreen shrub with a dense, upright habit that matures over time to 9-12’ tall. ‘Red Mill’ is a popular cultivar that is particularly noted for the fiery red color of its newly emerging foliage. Serrulate, oblanceolate to obovate-oblong leaves (to 2” long) emerge bright red in spring, then briefly transition to mahogany before maturing to dark green. Large pendulous clusters (racemes) of urn-shaped, lily-of-the-valley-like white flowers bloom in early spring (April). If spent flowers are not trimmed off after bloom, they are followed by small 5-valved capsules. Bead-like flower buds are set in late summer for the following year and provide winter interest and contrast to the evergreen foliage. 'Red Mill' typically matures in a spreading mound to 4-6' tall.
Dieback and leaf spot are occasional problems. Lace bug infestations can be a serious problem, particularly in the eastern U.S. Watch for mites, nematodes and scale.
This cultivar is ideal for foundations and foreground placements in the shrub border. Also effective in open woodland areas. Effective when mixed with other broadleaf evergreens. May be massed, grouped or grown as small specimens.