Abstract: A pulsating cleaning attachment is added to an existing rotary lawn mower, and is adapted to receive a hose for cleaning the mower blade and underside surface of the lawn mower carriage. An attachment body member of the attachment includes a first upward-directed water passage selected at an angle of about thirty degrees, which passage terminates in an elliptically-shaped opening on the inner surface of said body member. This passage both forms and directs a jet stream of water exiting therefrom into and from beneath a rotating blade tip of the mower, whereby the rotating blade cuts the jet stream and creates a pulsating cleaning action for the undercarriage, blade and skirt of the mower.