9 cm sized pot. Lobelia siphilitica is also known as the Great Blue Lobelia is a herbaceous perennial that typically grows in moist to wet locations in their native habitat. It is clump forming with rosettes of foliage over winter (easy to divide in early spring). It has toothed lance shaped leaves and spikes of brilliant blue flowers reaching 60 -90 cm high. Full sun or part shade in moist-wet soil. Flowers attract bees and beneficial insects.