Ceratostigma 'AUTUMN BLUE'

Visiting Mediterranean seaside resorts you must have noticed a handsome shrub with arching branches bearing sky blue flowers - plumbago auriculata. It is too tender for continental Europe, though, there are relatives that can deal with our winters and look very similar. They are generally called hardy plumbago and bear deeper blue flowers.

Autumn Blue is a dwarf or ground-covering variety of hardy plumbago. It bears gentian-blue, 5-petalled, 1-2 cm large flowers, borne in terminal clusters from August till the first frost. In hot summers the flowers appear early in the month, in average or cold summers from late August. Deciduous leaves are obovate, medium green, and in early autumn turn dark red to light burgundy red, and scarlet red and golden orange in lower parts while new flowers keep popping up offering a unique colour combination.

In the trade you can often come across its classification as a variety of c.plumaginoides, however, RHS confirms it is a hybrid, probably with c.willmottianum thanks to hairy leaf margins while c.plumbaginoides foliage is almost naked.

Hardy ground-covering plumbago does best in a position with plenty of sunlight yet slightly sheltered during the hottest afternoons of summer. It is soil tolerant but needs free draining soil. In the wild it usually grows in poor soil so make sure not to feed it too much - excess fertilizing might burn the roots. It is often used in larger rockeries where more plants are recommended to help cover larger areas. Remove all above-ground parts in early spring. Hardy to about -24°C (USDA zone 6).

Last update 10-08-2018