P. Indispensable low-growing perennials of shrubby habit with blue.
Ceratostigma Willmottianum grows to about 3 ft. in the open border but usually dies back to soil level in winter. Against a warm wall it usually grows taller. The flowers appear from July to the end of September. Ceratostigma plumbaginoides (Plumbago larpentae) has flowers resembling periwinkles in late summer, growing to about 1 ft. It is a first-rate rockery plant. The foliage frequently turns purplish-red at the same time. Both species may be increased by division in late spring.