Lobelia Siphilitica (Great Blue Lobelia) The perennial Lobelias have upright spikes of large flowers, not at all like the more familiar trailing types grown in hanging baskets. This easy-to-grow native species bears heads of dark blue to white flowers through late summer and fall, over dark-green leaves. Plants will usually self-sow, and the seedlings are easily moved while still small. Clumps may also be divided in early spring. Much more perennial in habit than most of the other hardy types. Attracts both butterflies and hummingbirds. Excellent for cutting. CAUTION: Harmful if eaten.