Great Blue Lobelia

Lobelia siphilitica is a native North American herbaceous perennial that produces racemes of tubular blue to blue-violet flowers from August through October, filling a gap when most perennials have finished. It grows naturally along stream banks, wet meadows, and woodland edges from eastern Canada through the central United States. Ruby-throated hummingbirds and long-tongued bumblebees are its primary pollinators, making it a high-value late-season wildlife plant.

The plant is short-lived, typically persisting two to four years, but self-seeds reliably in consistently moist soil. It fits naturally in rain gardens, pond margins, and low spots where other perennials fail. It tolerates part shade, which suits its preference for humid, sheltered sites. Mulching around the base retains the moisture it needs and suppresses competing vegetation. Soil pH between 5.5 and 7.0 is acceptable; slightly acidic conditions are ideal.

The species epithet siphilitica reflects documented use by several Native American nations as a treatment for syphilis, a practice later adopted by European settlers. The treatment was ineffective against the disease, but the plant contains lobeline and related piperidine alkaloids. Ethnobotanical records also note traditional use for colds, fevers, and intestinal parasites.