Family: Clusiaceae
Common Name: St John's Wort

There are over 400 species of annuals, perenni­als and shrubs in this genus which is endemic to temperate regions of the northern hemi­sphere. Many hybrids have also been devel­oped. They range from large, spreading or arch­ing shrubs to compact subshrubs to ground-covers. The foliage of shrubs and subshrubs is usually evergreen and often veined or dotted with black. The attractive, five-petalled flowers have masses of stamens at the centre and come in various shades of yellow. They flower for much of the year. Most species are vigorous growers and are used in borders, rock gardens and mixed shrub plantings, or as groundcover.

Species

H. calycinum, rose of Sharon or Aaron's beard, zone 6, a shrub to 60 cm (2 ft), has creeping stems and gold-yellow flowers, 5 cm (2 in) across.

H. forresti (Synonym: H. patulum var. forresti), zone 5, is a shrub, to about 1 m (3 ft) high, suitable for very cold areas.

H. x inodorum, zone 8, is an arching shrub of 1.5 m (5 ft), has fragrant leaves and flowers.

H. monogynum, zone 9, a spreading, semi-evergreen shrub, grows to 1 m (3 ft) tall.

H. x moseranum (H. calycinum x H. patulum), zone 7, an evergreen shrub, grows 30-60 cm (12-24 in) tall, with wide, saucer-shaped flow­ers.

H. olympicum, zone 6, is either an upright or trailing shrub, to 25 cm (10 in).

H. patulum, zone 6, an upright, evergreen shrub, with golden yellow flowers, grows to a height and spread of 1.5 m (5 ft).

H. perforatum, known as perforate St John's wort, zone 3, is a trouble-some weed, declared noxious in some countries.

H. prolificum, zone 4, is an evergreen shrub, to 2 m (6 ft), with small flowers.

Cultivation

Plant in well-drained soil in a sunny position, though some, like H. calycinum, do better in shade. Some need the protection of a wall or fence. Most require little pruning, while some benefit from pruning in early spring. The method of propagation depends on the species and may be from seed, from cuttings struck in sandy soil in a cold frame, or by division or from suckers.

Climate

There are species suited to various cli­matic zones.