Quick Guide: summer, hardy/ half-hardy, full sun, height: 3m/10ft, width: 2.1m/7ft

This large genus of attractive evergreen and deciduous shrubs is often known as Californian lilac, revealing its origin. Most bear clusters of heavenly blue flowers; a few are pink or white.

GROWING Set out young plants in late spring in light, welldrained soil. Most types, especially the evergreen, need the protection of a warm, sunny wall, but will grow in the open if sheltered from wind. Tie shoots and branches of evergreens to wall supports and trim lightly when needed. Prune deciduous varieties in spring by cutting the preceding year's growth back to 7.Scm/3in. Remove faded flowerheads from all types.

PROPAGATION Take 7.5cm/3in soft cuttings in summer; root in sandy compost under cover; pot on when rooted and plant out the following year.

VARIETIES Ceanothus x `Autumnal Blue', one of the hardier hybrids, evergreen, deep blue flowers; C. x `Burkwoodii', evergreen, light blue, slightly scented flowers; C. x `Gloire de Versailles', deciduous, panicles of powder blue flowers, a good choice for a sunny open site; C. impressus (above), half-hardy evergreen wall shrub, clusters of small deep blue flowers in spring; C. tbyrsiflorens repens, evergreen, forms mounds 90cm/3ft high, light blue flowers in late spring.

POSSIBLE PROBLEMS Soils high in lime may sometimes cause chlorosis.