Zones: 5 to 10
Size: To 3' tall and wide
Exposure: Sun, Filtered Sun, Part Shade
Small blue to lavender fluffy flowers in clusters in late summer to autumn. Dark green leaves, serrated. Spreads by rhizomes and can be aggressive. Prefers moist soil in full sun. Cut back to promote denser habit.
Published in Prodromus (A. P. de Candolle) 5: 135 in 1836.
Basionym is Eupatorium coelestinum L.
Native to eastern and central US and Cuba.
I was given a rooted cutting in October 2009 and planted it in the 'Wild Or Wacky' garden. It has not expanded out of bounds in 2 years, but the clump has got much bigger. It blooms reliably in late summer to autumn.