Great blue lobelia is an herbaceous perennial in the bellflower family (Campanulaecae) and is native to eastern North America. The genus was named to honor Matthias de l'Obel, a French physician and botanist who helped write a new plant classification system based upon leaves. The plant was believed to be a cure for syphilis; thus the species was given the unfortunate name of siphilitica . Great blue lobelia may grow 3 to 4 feet tall and 1 to 1.5 feet wide. It prefers wet to moist soil and partial sun. Full sun is tolerated if the soil is consistently moist. The soil should be fertile and loamy. This plant forms clumps that may be divided in spring and has been known to self-seed. Showy blue flowers first mature in mid-summer and continue into early fall. The flowers are larger than other lobelias and are attractive to pollinators. This plant may be used in a butterfly, native, pollinator or rain garden. It is also effective in borders, meadows, naturalized areas and near ponds or streams. The nectar and pollen of the flowers attract primarily bumblebees and other long-tongued bees. This plant was selected as the 1993 NC Wildflower of the Year , a program managed by the North Carolina Botanical Garden with some financial support from the Garden Club of North Carolina. Great blue lobelia is one of the 20 key pollinator plants that should be blooming in August for the Great Southeast Pollinator Census 2025. Fire Risk: This plant has a medium flammability rating. Insects, Diseases and Other Plant Problems: Snails and slugs may damage the foliage. More information on Lobelia .
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.
Dappled Sunlight (Shade through upper canopy all day) | 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 | Occasionally Wet
NC region
Mountains; Piedmont
Mature size
Height: 1 ft. 6 in. - 4 ft. 0 in. | Width: 1 ft. 0 in. - 1 ft. 6 in.
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Erect
Foliage
Deciduous
Leaf color
Green
Leaf arrangement
Alternate
Leaf shape
Lanceolate
Leaf margin
Dentate
Leaf size
3-6 inches long
Hairs present
No
Leaf detail
Great lobelia has finely-toothed, lance-shaped, light green leaves (to 5" long). The alternate, stalkless leaves are 2 to 6 inches long.
Flower color
Blue
Flower value
Showy
Flower form
Raceme
Flower shape
Tubular
Flower detail
Great lobelia is a clump-forming perennial which features an elongated cluster of light to dark blue, tubular, 2-lipped flowers with the three lobes of the lower lip appearing more prominent than the two lobes of the upper lip. The flowers arise from the upper leaf axils forming a dense terminal raceme atop stiff, unbranched, leafy stalks typically rising 2-3' tall. Its flowers are larger than other lobelias and have stripes on the tube portion. Blooms from July to October.
Bloom time
Fall; Summer
Fruit detail
Displays from August to November
Wildlife & Ecology
Native status
Native
Origin
Eastern North America
Distribution
AL, AR, CO, CT, DE, GA, IL, IN, IA, KS, KY, LA, ME, MD, MA, MI, MN, MS, MO, NE, NH, NJ, NY, NC, ND, OH, OK, PA, RI, SC, SD, TN, TX, VT, VA, WV, WI, WY
Wildlife value
Its flowers are attractive to hummingbirds and butterflies.