Quick Guide: summer, hardy, full sun, height 23cm/9in, width 15cm/6in

Phacelia campanularia, or California bluebell, is an annual plant whose bright blue, bell-shaped flowers bloom all summer and are attractive to bees. The dark green, rounded leaves are fragrant when crushed. Annuals are useful in the rock garden for introducing a change of colour for one season, or for filling a gap if a perennial becomes exhausted. This species is also good at the front of a border. There are no named varieties.

GROWING Well-drained, well-cultivated sandy soil is best, in a sunny situation.

PROPAGATION Sow seeds in shallow soil in spring, directly in the flowering site. Autumn-sown seedlings need protection over winter but produce earlier-flowering plants.

POSSIBLE PROBLEMS Slugs may damage seedlings.