Great Blue Lobelia, Lobelia siphilitica, is a lovely plant late in the growing season, when plants with yellow flowers are usually prominent. Tall spikes of brilliant true-blue flowers grow on a stiff, unbranched, leafy stalk, 1-3 feet high.
Flowers of this genus all have two narrow lobes or “ears” above, with three wider lobes forming a lip below. The 1-inch long violet-blue flowers of Great Blue Lobelia are striped with white on the three lower lobes, which appear more prominent than the lobes above. Leaves are alternate on the stem, finely toothed and pointed.
Great Blue Lobelia is a wetland native species, requiring wet to moist soil, fertile and loamy. The plant requires little maintenance, growing in part shade, but in full sun the soil must be consistently moist, as in rain gardens. The natural habitat is meadows, moist thickets and swamps from Maine to Manitoba and Colorado, south to North Carolina and Texas. While found in most counties of Virginia, it is infrequent in the Co...