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

Sisyrinchiums are handsome members of the iris family. Their erect flower spikes, clothed with star-shaped flowers of violet, blue or yellow, are useful for bringing height to a rock garden design. The fresh green leaves are long and narrow. Different species are in flower from spring through to autumn.

GROWING Plant between spring and autumn on well-drained soil into which plenty of peat or leaf-mould has been incorporated. Choose a site where the plants will not he disturbed. In autumn remove the dead leaves and stems.

PROPAGATION Species come true from seeds, which will germinate where they fall if the ground is undisturbed. Alternatively lift, divide, and replant in autumn or spring.

SPECIES S. striatum, reaches 45cm/18in, innumerable creamy-yellow flowers in mid summer; S. angustifolium, clumps of grassy leaves, violet flowers right through summer; S. grandiflorum, bell-shaped purple flowers in early spring; plant in close groups for best effect.

POSSIBLE PROBLEMS Generally trouble-free.