It is native to the eastern Himalayas, China, Korea, and Japan.

[2] This species produces annual stems up to 2 m (7 ft) tall and 0.5 in (1.3 cm) in diameter.

The abundant pink to purplish flowers bloom in late summer.

[3] Five subspecies are accepted:[1] The specific epithet thunbergii refers to the 18th-century Swedish botanist Carl Peter Thunberg.

[4] In cultivation this plant has gained the Royal Horticultural Society's Award of Garden Merit.