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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.
'Blue Eclipse' is a medium-sized deciduous climber, up to 3 metres high, with divided green leaves and large bell-like flowers of deep blue with a white edge on the outside and white inside, followed by fluffy seedheads
A. thomsonii is a clump-forming perennial, to 1m tall, with oval, toothed leaves, up to 10cm long, on hairy stems. Flowerheads, up to 5cm across, comprising lavender-blue rays and a central yellow disk, are held on slender branches from late summer into autumn
'Diana Clare' is a vigorous semi-evergreen perennial with narrow silvery-green leaves, lightly speckled with dark green near the margins, and violet-blue flowers from late winter to late spring
RCBAM3 is a perennial to around 50cm tall forming a mound of grey-green, bluntly-toothed, aromatic foliage. Relatively large, deep purple-blue flowers are borne in tiered whorls on long stems from late spring into summer
'Sky' is a herbaceous perennial 1.5m high with deciduous strap-shaped green leaves and flowerheads of long, tubular, sky-blue flowers, darker near the tips, which hang down as they open in late summer
'Hensol Harebell' is an erect herbaceous perennial to 90cm, with divided leaves tinted purple in late summer, and nodding, rich violet-blue flowers 5cm wide, with short, hooked spurs
E. ritro is a robust, upright herbaceous perennial, with jaggedy-divided, prickly dark green leaves whitish beneath. Rounded, violet-blue flower heads on silvery, branched, leafy stems
'Cambridge Blue' is a compact annual to 15cm, forming a low hummock of narrow foliage, with clear light blue, two-lipped flowers 2cm across in summer and autumn
Opal is a semi-evergreen perennial with ovate leaves heavily blotched and speckled with silver; clear pale blue flowers open from pale pink buds in spring on stems to 35cm tall
'Star Wars' is a n upright, bushy, deciduous shrub to 70cm tall with ovate, toothed leaves. The small, single flowers borne from summer into autumn have white tubes and sepals and violet-blue petals
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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.