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All ratings refer to the UK growing conditions unless otherwise stated. Minimum
temperature ranges (in degrees C) are shown in brackets
AGM plants have been through a rigorous trial and assessment programme. They are:
This plant will provide nectar and pollen for bees and the many other types of pollinating insects.
It is included in an evolving list of plants carefully researched and chosen by RHS experts. Divided into 3 groups these lists, linked below, are maintained by a team of RHS staff and are reviewed annually.
A. officinalis is typically biennial (occasionally perennial), producing many spikes of attractive blue flowers from mid-summer to first frost
A. arvensis is an annual plant that is hairy and bristly. Leaves are wavy, have an almost warty appearance and are narrow and pointed; upper leaves clasp the stem. Small blue, flared, tubular flowers are borne in clusters from early summer through to autumn
A. azurea is a herbaceous perennial to 90cm with coarsely-hairy, lance-shaped, mostly basal leaves. Bright gentian-blue flowers, aging to blue-purple, are borne on erect, branching stems
'Loddon Royalist' is an herbaceous perennial with coarsely hairy, lance-shaped, mostly basal leaves. Intense deep blue flowers 15mm across are borne on erect, branching stems
B. macrophylla is an herbaceous perennial forming a clump to 45cm, with broad sprays of small, clear blue flowers, followed by large heart-shaped, long stalked leaves
P. sempervirens is a coarse, bristly, tap-rooted perennial with a basal rosette of pointed, oval leaves up to 40cm long. Upright stems carrying smaller leaves, are topped with sprays of bright blue, forget-me-not flowers in spring and early summer
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We're a UK charity established to share the best in gardening. We want to enrich everyone's life through plants, and make the UK a greener and more beautiful place.