Abstract: Apparatus for trimming plants, which apparatus includes at least one handle and a rotating, powered trimming head, which trimming head includes at least one flexible, filament-type trimming element, especially a synthetic or plastic filament or thread end-section, extending beyond the periphery of the housing for the trimming head, which trimming element is wound on a spool provided in the housing. The end-section can be adjusted by a predetermined amount during operation of the apparatus by the intervention of a coupling element whereby the spool is rotated relative to the housing through a predetermined angle, with the coupling element being movable from a lock position to a release position by means of centrifugal forces.