Great Blue Lobelia (Lobelia siphilitica)

Great Blue Lobelia (Lobelia siphilitica)

Great Blue Lobelia is Cardinal Flower's blue counterpart — equally tall, equally dramatic, and equally beloved by hummingbirds and bumblebees, but in a rich blue-violet that provides the perfect cool complement to Cardinal Flower's burning scarlet. Planted together at the bayou's edge, the two Lobelias create one of the most spectacular late-summer wildflower combinations in the native plant world.

Botanical Profile

• Family: Campanulaceae (Bellflower family)
• Native Range: Eastern and central North America from Maine to North Carolina and west to Kansas; native to Louisiana's stream banks, bayou edges, and moist woodland margins
• USDA Hardiness Zones: 4–9
• Mature Size: 2–4 feet tall
• Bloom Time: August–October
• Sun: Full sun to part shade
• Soil: Moist to wet; tolerates clay and periodic flooding; thrives along bayou edges and in rain gardens

Ecological Role

Great Blue Lobelia's blue-violet tubular flowers attract ruby-throated hummingbirds, bumblebees — which are strong enough to force their way into the flowers — and specialist long-tongued native bees. Its late bloom window — August through October — makes it a critical nectar source during the fall migration period. It self-seeds freely along moist garden edges, maintaining colonies for years. Its scientific name — siphilitica — reflects its historical use by Indigenous peoples as a treatment for syphilis, a use that was communicated to European colonists and led to extensive (ultimately unsuccessful) trials of the plant as a cure.

In the Living Canopy & Understory

Part of the Jardin — The Living Canopy & Understory collection at Big Mamou Enterprises, Great Blue Lobelia is Cardinal Flower's perfect partner — blue to its red, cool to its fire, and equally irresistible to the hummingbirds of the Louisiana bayou.