A patch of Great Willowherb (Epilobium hirsutum) has self-seeded in the garden. As it happens I'd been wondering what tall, late summer flowering perennial would look good there so the decision has been made for me! Seek and ye shall find?

 In fact with that in mind I had already planted several pots of the white flowered form of Rosebay Willowherb (Chamanerion angustifolium 'Album') which seems to be establishing itself. Willowherbs can be invasive but the combination of the two growing through each other should be pleasing.
 'Album' is said to be less vigorous (and is rarer) than the very widespread rose-pink form of C. angustifolium which is a common site at this time of year. The drifts of colour can often be spotted along railway lines and roadsides; too rampant to be a garden plant but very attractive...