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.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
High Organic Matter
Soil drainage
Moist | Occasional Flooding
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 1 ft. 6 in. - 3 ft. 0 in. | Width: 1 ft. 6 in. - 3 ft. 0 in.
Growth rate
Rapid
Maintenance
High
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Clumping; Spreading
Texture
Medium
Foliage
Deciduous
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Opposite
Leaf shape
Cuneate; Deltoid; Ovate
Leaf margin
Dentate; Serrate
Leaf size
1-3 inches long
Hairs present
No
Leaf detail
Coarsely-toothed, ovate-deltoid leaves are up to 3 inches long and 2 inches wide. The light green upper surface has a conspicuous network of veins. Tips are bluntly pointed.
Flower color
Blue; Pink; Purple/Lavender
Flower value
Long Bloom Season; Showy
Flower form
Corymb
Flower shape
Tubular
Flower size
< 1 inch
Flower detail
Flat-topped clusters of disc flowers that lack rays. It has numerous small, fluffy, tubular, blue-purple flowers (to 1/ 2” across) andt blooms from July to October.
Bloom time
Fall; Summer
Fruit detail
Displays from August to November
Stem color
Green; Purple/Lavender; Red/Burgundy
Stem detail
Downy purplish stems
Wildlife & Ecology
Native status
Native
Origin
Canada, Cuba, southeastern United States, NC
Distribution
AL, AR, DC, DE, FL, GA, IL, IN, KS, KY, LA, MD, MI, MO, MS, NC, NE, NJ, NY, OH, OK, PA, SC, TN, TX, VA, WV
Wildlife value
The nectar-rich flowers are attractive to butterflies and other pollinators. Birds enjoy the seeds.