Blue Mistflower or Ageratum, Conoclinium coelestinum

Commonly called mistflower, this late summer to fall-blooming herbaceous perennial has 8 weeks of blue flowers from late summer until frost. It is nectar-rich and pollinators love it.

This plant prefers moist humusy soils that do not dry out in full sun to partial shade areas. Blueish purple flowers are fluffy, tubular (to 1/ 2” across). Cut back taller plants in spring to prevent flopping.

This is a great plant to consider for a wildflower garden or naturalized area, does especially well around pond borders as long as spreading roots will not affect other plants. It is not recommended for smaller planting areas as it spreads aggressively by its rhizomes and self-seeding. Propagate by clump division in early spring. This plant is moderately resistant to damage from deer.

Photo by Eleanor CC BY-NC 2.0

Sources:,, other authoritative resources and personal experience.