Quick Guide: summer, hardy, semi-shade, height:15cm/6in, width: 30cm/12in

A number of gentians are in cultivation, with widely varying requirements and flowering times. Broadly speaking, these perennials are divided into European species, which are spring flowering, and the Asiatic species described here which flower in the autumn. The flowers are large, trumpet-shaped and of a uniquely intense blue. They are among the most distinguished alpine plants.

GROWING Plant out in spring, in deep soil previously enriched with leaf-mould or peat. Do not let the soil dry out. Always check the lime-tolerance of individual species.

PROPAGATION Lift, divide and replant in spring. All species may be raised from cuttings taken from the basal shoots in spring and treated as for helianthemums.

SPECIES Gentiana sino-ornata,, easy to grow in acid soil, abundant 5cm/2in long deep blue flowers striped purplish blue, a much admired species; G. farreri, lime-tolerant, clear light blue flowers with white throats from late summer; G. x `Stevenagensis', strong-growing prostrate hybrid, deep purple blue, late summer.

POSSIBLE PROBLEMS Root rot on poorly drained soil.