x-Aster tongolensis 'Berggarten'
No garden is complete in autumn without a Michelmas daisy and Aster tongolensis 'Berggarten' is an immensely pretty one.
A creeping, mat forming perennial it is quite different from the taller, more familiar species and starts flowering right at the start of summer. Its fine- petalled, lavender-blue daisy rays are dotted with soft orange centres and will bloom from now, right up until the frosts. It is hardy, thriving in full sun or partial shade and, although it prefers fertile soil, like most asters, it's not fussy and will cope just about anywhere, except in damp or boggy ground. Give it a free draining spot and add compost when planting and it will thrive. Unlike many of its cousins there is no need to stake the almost leafless stems of 'Bergartten' and it is resilient to powdery mildew, the common curse of many of its family.
This aster looks lovely in groups, planted en masse, so buy as many plants as you can, or gradually increase stock yourself by dividing plants in spring. Unlike other herbaceous perennials however, asters must only be split in the spring rather than the autumn - they do not appreciate being disturbed so soon after all their hard work flowering. Wait until new shoots are being formed in the spring and they will happily send out new roots too. Lift the whole clump and split with a sharp spade or back-to-back forks and replant the new pieces, adding compost and watering them in well.
'Berggarten' is at home amongst other daisy flowers like golden rudbeckias or osteospermum, or even the taller asters, such as Aster novae-angliae 'Harrington's Pink' or the purple 'Eye End Beauty'. Grow with contrasting flower shapes such as penstemmons or spiky grasses or blend with the gentle, pastel shades of Japanese anemones. The hazy clouds of blue flowers are also laden with pollen and nectar and loved by butterflies and other pollinators, making them perfect on the edge of a wildlife garden.