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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.
'Kestrel' is a strong-growing upright perennial to 2m tall, with large, dark green leaves and semi-double, rich blue flowers to 6.5cm across, in spikes to 90cm long, with many side branches, flowering in early summer
I. magnifica is a bulbous perennial to 50cm in height, with arching, glossy green leaves and 2-6 pale lilac flowers 8cm in width from the leaf axils in late spring, the falls near-white with a yellow centre line
S. verna is a dwarf bulbous perennial to 20cm, with linear leaves and small, starry violet-blue flowers in a dense raceme or corymb in early spring
'Wild Swan' is a hybrid which probably has an early-flowering mountain species A. rupicola, and the more familiar autumn-flowering Japanese A. hupehensis, in its parentage, giving this recent introduction a very long, intermittent flowering season. It has white flowers with a blue reverse, and flourishes in dappled shade. Winner of the RHS Chelsea Flower Show Plant of the Year Award in 2011
'Grand Maître' is a cultivar that produces light blue flowers, with orange stamens and stigma, in early spring
'Blue Star' is a compact herbaceous perennial to 75cm, with narrow bright green leaves and pale lavender-blue flowers 12mm wide, in large sprays
T. laxa is a perennial with linear basal leaves and loose umbels of funnel-shaped, mid- to deep blue flowers 3-4cm in length, on stems to 50cm in early summer
L. × speciosa are clump-forming perennials, often grown as annuals or biennials, with basal rosettes of pale to dark green, bronzy, red-flushed or dark red foliage. In summer and early autumn they produce dense, upright spires of two-lipped, tubular flowers in shades of red, pink, purple or blue
Black Scallop is a usually-evergreen creeping perennial with very glossy, dark, near-black, scalloped leaves, and short spikes of deep blue flowers in late spring and early summer. The leaves will become darker in lighter, colder conditions
'Purple Queen' is a woody-based perennial or tender shrub, to 75cm tall, with small, narrowly-oblong, aromatic leaves and 30cm spikes of smooth, deep purple-blue flowers, each up to 2.5cm long, in summer and autumn
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