Lobelia

Lobelia erinus is a compact, spreading annual or tender perennial grown for a long display of small flowers. Depending on cultivar, the flowers may be blue, violet, pink, white, or red, and the stems may form a tidy edging or trail over a container. It performs best through cool weather and can pause flowering during summer heat. ## Garden Use Use edging lobelia along a border, in a container, or in a raised planter where its low stems can spill gently over the edge. The species is typically about 0–12 inches tall and spreads about 1–2 feet; cultivars vary in habit and size. It is generally grown as an annual outside mild USDA zones 10–11, though it may persist there as a tender perennial. ## Growing Conditions Plant in fertile, well-drained soil that stays evenly moist. Full sun suits cool summers; provide partial shade in hotter regions. Regular moisture is important, and the plant may stop flowering when temperatures rise, then resume as conditions cool. The [UF/IFAS plant profile](https://ask.ifas.ufl.edu/publication/FP351) and [North Carolina Extension profile](https://plants.ces.ncsu.edu/plants/lobelia-erinus/) describe its cool-season performance, moisture needs, colors, and uses. ## Maintenance After a flush of flowers, shear or trim the plant to encourage fresh growth and another bloom cycle. Keep the root zone moist, especially in warm weather, and avoid persistently waterlogged soil, which can encourage stem or root rot.