Lithospermum (now re-named Lithodora by the botanists) is a ground cover plant – its blue, funnel-shaped flowers are as bright as anything you will find in the summer rock garden. It requires a sunny spot and humus-rich soil – add peat or compost at planting time. If your soil is chalky, do not plant L. diffusum or its varieties – choose instead the lime-tolerant L. oleifolium.

VARIETIES: The best known species is L. diffusum; height 6 in., spread 2 ft.

Flowering period: June-September. The prostrate mat spreadsquickly-the leaves are dark green and the blooms deep blue. The species is rarely grown – the choice is between the varieties ‘Heavenly Blue’ and ‘Grace Ward’. Most experts vote for ‘Grace Ward’. L. oleifolium is quite different in colour – the leaves are silvery grey and the flowers change from pink when in bud to pale blue when fully open. Its basic details are height 6 in., spread 1 ft.

SITE AND SOIL: Any well-drained, moist soil – thrives best in full sun.

PROPAGATION: Plant cuttings in a cold frame in midsummer.

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