This erect, herbaceous wildflower brings long-blooming, purple spires to beds, borders, and wetter areas. Commonly found on streambanks and in moist meadows, blue vervain has a preference for soggy conditions (it’s also called swamp verbena) and full sun, though it will grow up to 5 feet tall in a variety of average soils and part sun. From mid-summer until fall, pencil-like spires of flowers bloom in candelabra-shaped panicles. A ring of small, blue-violet flowers appears to ascend upwards from the bottom of the spike to the tip, attracting bees and other important pollinators. Vervain tolerates standing water, drought, and partial sun and spreads by rhizomes and self-seeding. To encourage bushier growth and branching, pinch off the tops of the plants several times during the growing season.
 
Native habitats include stream banks, moist meadows, wetlands, marshes, and ditches. Vervain is a good candidate for beds and borders, rain and butterfly gardens, slopes, or locations near ponds and rivers. It’s an excellent substitute for non-native species, including purple loosestrife and purple foxglove.
 
Plant Characteristics:
Reaches 3-5' tall and 1-3' wide.
 
Does best in full sun; tolerates part sun.
 
Prefers fertile loam or average-to-wet soils, including clay and sand.
 
Purplish-blue flowers bloom in multiple, elongated panicles about 2-5” long. Each flower has a blue-violet corolla with five lobes, a tubular calyx, and four stamens. Blooms give way to four oblong, reddish-brown nutlets.
 
Toothed, lance-shaped green leaves ascend in pairs up the hairy, square stem and are about 6” long with pointed tips.
 
Wildlife Value:
Host plant for 11 species of Lepidoptera larvae, including specialist the common buckeye butterfly, bilobed looper (shown here) and spotted phosphila moths, and specialist verbena groundling moth. Long- and short-tongued bees collect the nectar and sometimes the pollen. Other bee pollinators include epoline cuckoo, eucerine miner, halictid, and the verbena bee, a specialist pollinator. Thread-waisted wasps, bee flies, thick-headed flies, and golden soldier beetles also visit blue vervain. Cardinals, sparrows, juncos, and other songbirds and small mammals like to eat the seeds.
 
Medicinal, Edible, and Other Uses:
Historically the roots, leaves and flowers have been widely used to treat conditions such as stomach aches, colds, cramps, depression, fever, headaches, bruises, and arthritis. Externally, it has been applied to wounds and acne. The Iroquois used a cold infusion of mashed leaves "to make obnoxious persons go away."
 
Blue vervain can interfere with blood pressure medication and hormone therapy, and large doses cause vomiting and diarrhea.