Great Blue Lobelia

Great Blue Lobelia (*Lobelia siphilitica*) is a stunning native wildflower of eastern North America, producing tall spikes of vivid blue-violet to true blue flowers from late summer through fall in moist meadows, stream banks, and woodland edges. The blue-flowered counterpart to the scarlet Cardinal Flower, it shares the same genus and habitat preferences and is equally important ecologically, serving as a primary nectar source for bumble bees, which are the principal pollinators of this species. Its deep, rich blue color — rare in the late-season wildflower palette — makes it an invaluable addition to native gardens.

The individual flowers of Great Blue Lobelia are tubular and two-lipped like those of Cardinal Flower, with the lower lip marked by a white stripe that serves as a nectar guide for pollinators. The flowers are densely arranged along robust, upright spikes reaching 1 to 3 feet tall, which emerge from a rosette of toothed, lance-shaped basal leaves. The plant's curious species name 'siphilitica' reflects a mistaken historical belief — introduced to European physicians by Native Americans — that the root was a cure for syphilis, a claim that proved unfounded but has persisted in the plant's scientific name.

In native plant gardens, Great Blue Lobelia is most powerful when planted alongside Cardinal Flower, creating a striking red-and-blue native combination that blooms simultaneously in late summer and attracts an extraordinarily diverse array of pollinators. While Cardinal Flower primarily attracts hummingbirds, Great Blue Lobelia is the preferred nectar source for bumble bees, creating a garden that serves multiple pollinator guilds. It naturalizes prolifically by self-seeding along moist areas and can form large, lush colonies in rain gardens, bioswales, or pond margins.

Great Blue Lobelia is considerably more shade-tolerant than many native wildflowers and will bloom successfully under light deciduous canopy as long as consistent soil moisture is maintained. It is a short-lived perennial (2–4 years) but is highly reliable from seed and self-seeds prolifically when content. Unlike Cardinal Flower, it also contains toxic alkaloids and should be kept away from pets. For more moist-habitat native wildflowers, explore our full Flower Identifier database.