Conoclinium coelestinum

Ageratum is an herbaceous perennial native to the Eastern United States and is a member of the aster family (Asteraceae). It looks like the annual ageratum and because of that is sometimes called hardy ageratum. 

Ageratum prefers full sun to partial shade and moist, humus-rich soils that do not dry out. It grows 18 inches to 3 feet tall and wide. Taller plants may be cut back in spring to prevent flopping. It spreads by rhizomes and self-seeding. Propagate ageratum by clump division in early spring. 

It is a showy native plant that is found growing along roadsides on moist ditch banks. It flowers from late summer until frost and attracts pollinators and songbirds. Ageratum is moderately resistant to damage from deer.

This is a great plant to consider for a wildflower, pollinator, native or water garden and for naturalized areas. It does especially well around pond borders as long as spreading roots will not affect other plants. It is not recommended for smaller planting areas due to its aggressive nature. 

This is one of the 20 key pollinator plants that should be blooming in August for the Great Southeast Pollinator Census 2025.

Quick ID Hints:

• It is an erect herb with clusters of small heads of tubular flowers.
• Flowers are bluish-purple.
• Leaves are opposite, deltoidly ovate, crenately serrated.

Insects, Diseases, or Other Plant Problems: Leaf miners and aphids may visit and it is somewhat susceptible to powdery mildew. Taller plants may need support. It can spread and become a little weedy.