No other bedding plants exhibit such rich blue as trailing lobelia, Lobelia erinus. Cultivars with white, purplish pink, purple or sky blue bloom are still not quite as popular as the favorite cobalt blue bloom. Individual flowers are tiny but very profuse and uniform. Some have white centers. The narrow leaves are tiny as well, and finely textured. Some cultivars have dark purplish bronzed foliage.
Individual plants are only about three to six inches high and wide. Cultivars that are more rounded and densely foliated are excellent for edging. They are very popularly planted in single rows, and alternating with alyssum. Trailing types exhibit wispier growth that stays a bit lower and spreads a bit wider. They do not trail far, but cascades nicely from urns and hanging pots of mixed annuals.
Although grown as a warm season annual, trailing lobelia can survive as a short term perennial where winters are mild. Fresh new growth develops out of the centers of overwintered plants about now. If pressed gently into the soil just before they are replaced by new growth, scraggly outer stems can develop roots. They just might grow into new plants before the originals eventually die off.