Culture
Winter hardy to USDA Zones 7-10 where it is best grown in humusy, organically rich, moderately fertile, medium moisture, well-drained soils in full sun. Appreciates some part afternoon shade in hot summer climates. Avoid overwatering. North of Zone 7, plants may be brought indoors in containers for overwintering in a bright, cool, dry location in a sun room or greenhouse. If outdoor growth is attempted in Zone 6, site plants in sheltered locations and apply a winter mulch to protect the rhizomes.
Noteworthy Characteristics
Rehmannia glutinosa, commonly known as Chinese foxglove, is a rhizomatous, basal-leaved, rosette-forming, herbaceous perennial that produces a showy late spring to early summer bloom of pendant, tubular, foxglove-like, reddish-brown to yellowish-brown flowers with dark purple veins and purplish throats. Flowers (each to 2” long) bloom in few-flowered spike-like terminal racemes or singly from leaf axils on purplish stems rising to 1’ tall from a basal rosette of coarsely toothed, obovate to oblong, rosulate leaves (to 3-5” long). Fruits are many seeded capsules. This species is native to mountain slopes and open woodland areas in China.
Chinese foxglove (Chinese name of di huang) is one of the 50 fundamental herbs used in traditional Chinese medicine. Roots are used to treat a number of aliments including adrenal and renal disorders.
Genus name honors Joseph Rehmann (1753-1831) German physician and botanist who settled in St. Petersburg.
Specific epithet comes from the Latin word glutinosus meaning sticky or gluey in reference to the somewhat sticky condition of the leaves, stems and cooked roots.
Problems
No serious insect or disease problems. Slugs and snails may appear. Overly moist soils, particularly in winter, can lead to root rot.
Uses
Cultivated as a medicinal plant in China. Grown primarily as an ornamental plant in the U. S. where it serves as an interesting addition to border fronts, rock gardens and herb gardens.