This group of hardy herbaceous perennials contains many species, and most have small, brightly colouredin shades of blue, violet, pink and purple. They do well in borders, as ground cover and in rock gardens.
Suitable site and soil. Generally, they will grow in most soils but do best in one that is well drained in a spot where there is plenty of sun.
Cultivation and care. Plant out during autumn or spring. Tall species may need support from twigs. A second flowering and compact growth can be encouraged byback old flowering to just above the soil.
Propagation. Propagate byin a cold frame in spring or by division in spring.
Recommended varieties. G. psilostemon, a tall species withthat change colour during the year, is excellent in a sunny border. It is 75cm – 2 1 – 2ft high and wide and has brilliant magenta with dark centres in midsummer. A good variety is ‘Bressingham Flair’. G. macrorrhizum makes a good carpeting plant and spreads rapidly growing to 30cm – 12in high. The aromatic go scarlet in autumn; the flowers are either magenta or, in the variety ‘Ingwersen’s Variety’, rose-pink. G. ‘Johnson’s Blue’ is a hardy border plant with blue-mauve flowers in the middle of summer. The leaves are interestingly shaped with deep lobes and the plants grow to 40cm – 16in high by 60cm – 24in wide.
Pests and diseases. Watch out for slug attack.
FILLING THE CRACKS
G. sanguineum not only does well in the rock garden but also fills a bare path or paved area. Plant it in soil in the crevices between slabs, where water drains and it soon covers the stones with vibrant pink.