Each plant needs one particular virtue to earn its place in the rock garden – Onosma’s virtue is its long flowering season. The firstopen in spring and continue to appear until late summer. The narrow, bristly are evergreen and form compact clumps. The upright stalks bearing the flowers bend over at the apex, so that the clusters of long tubular flowers are pendent. Sunny and dry conditions are essential – the place for Onosma is in the crevice between rocks or on a dry wall. This plant does not like being disturbed.
VARIETIES: The most popular species is O. tauricum – height 8 in., spread 9 in.
Flowering period: April-August. The yellow flowers are fragrant and about 0.5 in. long. O. albo-roseum is quite similar but comes into bloom later and the flowers are white with a pink flush at the mouth.
SITE AND SOIL: A well-drained, sandy soil and full sun are essential.
PROPAGATION: Plantin a cold frame in summer.
By careful selection you can ensure that your rockery will have flowers nearly all year round. For each month there is a list of perennials which can be expected to be in full bloom – remember that some of these plants may come into flower earlier and can continue to bloom for many weeks afterwards.