Family: Verbenaceae
Common Name: Blue Spiraea, Bluebeard

These low-growing, rather spreading, deciduous shrubs and perennials from eastern Asia have opposite, toothed, aromatic leaves and generally blue flowers which bloom in late summer and autumn. They are commonly grown in mixed and shrub borders and are valued for their late flowers: massed planting gives the best effect.

Species

C. incana, bluebeard, is a shrub, often treated as a perennial. It grows to 1.5 m (5 ft) with ovate leaves, grayish-downy on the undersides, and blue to violet, autumn flowers. 'Candida' has white flowers.

C. x clandonensis, a hybrid of C. incana x C. mongholica, has vigorous gray-green foliage and lavender blue flowers. This bushy plant grows to 1 m (3 ft). Various attractive cultivars are available.

Cultivation

These plants like sun and a free-draining soil that is not too heavy. Plant in spring and protect from frost for the first winter. They are frost-hardy once established. Prune reasonably severely in spring, cutting back the old growth to within two buds from the base. After pruning, feed generously to encourage growth and abundant flowers. Propagate species from seed sown in autumn and germinated in a cold frame, and species and cultivars from softwood cuttings in spring, rooted in a greenhouse. In early summer, greenwood cuttings can be taken and these are slightly easier to root, again under cover.

Climate

Zone 6 for C. incana, zone 7 for C. clandonesis.