Ground covers, Perennials
Valued for clusters of intense blue, phloxlike flowers that bloom in summer to late fall, when cool hues are often especially welcome in the garden. (For pale blue-flowered Cape plumbago, see Plumbago auriculata.) Tolerates inconsistent watering. Shrubby species are usually treated like perennials in colder zones; cut them back after bloom and apply a thick mulch.
Native to China. Wiry-stemmed ground cover to 6–12 in. high. Bronzy to dark green, 3-in.-long leaves turn reddish brown with frosts. Blooms well only in areas with long growing season. Most striking in early or midautumn, when blue blossoms contrast with red fall foliage. In loose soil and where growing season is long, spreads rapidly and (eventually) widely by underground stems. Plant 1 to 1 1/2 ft. apart for quick cover. When plants show signs of aging, dig up and replace with rooted stems in spring or summer.