A large genus of some 250 species of mainly perennial plants, which contain a number of good garden plants They are mainly characterized by their blue flowers and greyish foliage. The colour of the flowers varies from soft, mauvy blues to bright violet ones, the softer tones being particularly suitable for romantic settings. The flowers are tubular with a lip and hood, much in the manner of a mint, and are carried in airy spikes.
The foliage on many of the more popular forms is a soft silver-grey that adds to the mistiness and romanticism of the plants, especially since they have a tendency to flop around. This silver colour is due to a covering of soft hairs, but not all have it and most of the more upright species have green foliage. They generally like a sunny position with a well-drained but moisture-retentive soil that is reasonably fertile. The floppier ones can be cut down after their first flush of flowers and they will produce new stronger growth with a fresh flush of leaves and flowers. Increase from basal cuttings in spring.