How to prune edging lobelia

Midsummer, after the first main flush fades; repeat in early autumn if needed. Use scissors or shears to cut the entire plant back by about half, removing the bulk of the old flowering stems. Water well and apply a dilute liquid fertiliser. New shoots emerge within a week or two and a fresh flush of bloom follows.

Once or twice per season: midsummer cutback is essential, with a second trim in early autumn if plants slow again. Edging lobelia (Lobelia erinus) benefits greatly from shearing back after the main summer flush. Cut plants back by half when flowering slows; they regrow quickly and produce a fresh display in late summer and autumn. Without cutting back, plants become sparse and stop blooming well. Regular trimming is the single most effective maintenance step for this popular annual.

Use scissors or shears to cut the entire plant back by about half, removing the bulk of the old flowering stems. Water well and apply a dilute liquid fertiliser. New shoots emerge within a week or two and a fresh flush of bloom follows.