Blue vervain is a native wildflower that spreads slowly through rhizomes and self-seeding. It can grow in disturbed sites and is commonly found in moist meadows, thickets, pastures, riversides, marshes, ditches, and river-bottom prairies. In NC it is found in only a few counties of the coastal, Piedmont and mountain areas. The plant forms clumps of stiff upright stems with lanced-shaped leaves with toothed margins. The purple flowers occur in a candelabra-shaped panicle and are a high-value nectar plant with a long bloom season. Blooms open bottom to top with only a few open at one time in mid to late summer. Plant in full sun to partial shade in average medium to wet soils and pinch the tops to encourage branching and a bushier growth habit. Use this plant in moist sites as around ponds, bogs or water and rain gardens.
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
Clay; Loam (Silt); Sand
Soil drainage
Moist | Occasionally Wet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 2 ft. 0 in. - 5 ft. 0 in. | Width: 1 ft. 0 in. - 2 ft. 6 in.
Growth rate
Medium
Maintenance
Low
Canopy layer
4 - Herbaceous (3-15 ft)
Form & Appearance
Habit / form
Erect
Leaf color
Green
Leaf type
Simple
Leaf arrangement
Opposite
Leaf shape
Lanceolate
Leaf margin
Serrate
Leaf size
3-6 inches long, 1-3 inches wide
Hairs present
No
Leaf detail
Up to 6 in long x 1 in wide, toothed, lance-shaped leaves with conspicuous veins that occur in pairs on the stem.
Flower color
Blue; Purple/Lavender
Flower value
Long-lasting; Showy
Flower form
Panicle
Flower shape
Tubular
Flower size
< 1 inch
Flower detail
Showy, 6-inch panicles of purplish-blue flowers. 1/4 inch individual blooms have a blue-violet corolla with 5 spreading lobes, a short-tubular calyx with 5 narrow teeth, 4 inserted stamens, and a pistil. Panicles appear candelabra-like with pencil-thin flower spikes. They bloom bottom to top with only a few open at a time.
Bloom time
Summer
Fruit color
Brown/Copper; Red/Burgundy
Fruit type
Nut
Fruit detail
The calyx persists and encloses 4 oblong, reddish-brown, triangular-convex “nutlets.”
Stem color
Green; Red/Burgundy
Stem detail
Stems are square and green or red with white appressed hairs.
Wildlife & Ecology
Native status
Native
Origin
North America
Distribution
AL , AR , AZ , CA , CO , CT , DC , DE , GA , IA , ID , IL , IN , KS , KY , LA , MA , MD , ME , MI , MN , MO , MS , MT , NC , ND , NE , NH , NJ , NM , NV , NY , OH , OK , OR , PA , RI , SC , SD , TN , TX , UT , VA , VT , WA , WI , WV , WY Canada: NB , NS , ON , QC
Wildlife value
Cardinals, sparrows, and juncos eat the seeds. Cottontail rabbits eat the foliage, however, most mammals avoid its bitter taste. Larval host plant for verbena moth and the common buckeye butterfly. Long and short-tongued bees collect the nectar and sometimes the pollen. Other bee pollinators include epoline cuckoo bees, eucerine miner bees, halictid bees, and the verbena bee (a specialist pollinator). In addition, the thread-waisted wasp, bee flies, thick-headed flies and golden soldier beetle are also known to all visit blue vervain.
It has been used for many years as a medicinal herb for treating convalescents and people suffering from depression, headaches, jaundice, cramps, coughs and fevers. Externally, it has been applied to wounds, ulcers and acne. Swamp vervain can, however, interfere with blood pressure medication and hormone therapy, and large doses cause vomiting and diarrhea.
Landscape Use
Landscape location
Meadow; Naturalized Area; Pond
Landscape theme
Native Garden; Pollinator Garden; Rain Garden; Water Garden