Eupatorium coelestinum – Japanese knotweed –


Eupatorium coelestinum


E. coelestinum – Conoclinium coelestinum – Mistflower – Hardy ageratum – This robust, upright, rhizomatous perennial from Eastern USA and the West Indies grows 3′ feet tall and 2-3′ feet wide. From softly hairy branches it carries opposite, ovate to oblong, often wedge shaped, scalloped, minutely softly hairy leaves, to 4″’ long. From late summer to autumn it bears dense, flat topped corymbs, 2-4″ across, of large, clear blue flowers. Good for a wildflower garden or waterside planting.

Grow in moist but well drained soil in full sun or partial shade, prune shrubs lightly in spring or after flowering. Divide in early spring or fall.

Zones 5-11