Each flower on the raceme of Great Blue Lobelia is two-lipped. The upper lip has two lobes while the lower has three. Photo Credit: Trish Beckjord
Great Blue Lobelia
Great Blue Lobelia (Lobelia siphilitica) is a lovely late summer/early fall-blooming native wildflower that is perfect for including in rain gardens, moist pond edges, and partially-shaded damp places. This wildflower grows as a 1-4’ tall (typically 2-3’) upright stalk that terminates in a raceme of blue-violet two-lipped flowers that bloom for about two months. The color of the flower creates a nice contrast to the goldenrods and Showy Black-eyed Susan that bloom at the same time. In my rain garden it is paired with Riddell’s Goldenrod (Solidago riddellii) and Turtlehead (Chelone glabra).
In the wild Great Blue Lobelia prefers moist soil with some organic content and partial shade. It is typically found in low, wet areas along rivers and ponds, bottomland woods and seeps, ditches and moist open fields. Where it is happy in a garden with moist to wet soils and some shade, it can form small attractive colonies. If grown in full sun, this plant will be more successful if the ground remains moist. In my garden, Great Blue Lobelia has done just that, establishing new plants in a partially shaded area that receives overflow runoff from my rain barrel.
This species is longer-lived and a more reliable perennial than its more flamboyant red cousin, Cardinal Flower (Lobelia cardinalis) which blooms at the same time. Great Blue Lobelia attracts hummingbirds and some large butterflies but bumblebees and other long-tongued bees are the primary visitors and pollinators. The caterpillar of the Pink-washed Looper Moth (love the name!) also feeds on the leaves. This plant is not typically eaten by deer or rabbits because the leaves contain toxic alkaloids that, when eaten, produce symptoms similar to nicotine poisoning. This affords some protection against predation.
Other than during its season of bloom Great Blue Lobelia is unremarkable, but the beautiful color of the flower makes it well worth including!