Great Blue Lobelia (Lobelia siphilitica), also known as Blue Cardinal Flower, is a herbaceous perennial native to eastern and central North America. Typically reaching heights of 2 to 3 feet, it features sturdy, unbranched stems adorned with lance-shaped, finely toothed green leaves arranged alternately. From July to October, this plant produces striking spikes of tubular, two-lipped blue flowers, with the three lobes of the lower lip appearing more prominent than the two lobes of the upper lip. These vibrant blooms add a splash of color to moist meadows, woodland edges, and stream banks.
Great Blue Lobelia thrives in full sun to partial shade and prefers rich, humusy, medium to wet soils. It is commonly found in moist to wet locations along streams, springs, swamps, meadows, and low wooded areas. Hardy in USDA Zones 4 through 9, it is an excellent choice for rain gardens, pollinator gardens, and naturalized areas. The plant may self-seed under optimal conditions, forming attractive colonies.
Ecologically, Lobelia siphilitica plays a significant role in supporting pollinators. Its nectar-rich flowers attract a variety of insects, including bees and butterflies, and are particularly favored by bumblebees, which are strong enough to pry open the flower's petals to access the nectar. Additionally, hummingbirds are known to visit the blooms, adding to the plant's wildlife appeal.
