A reel mower has a traction frame which carries one or more reel cutting units. Each cutting unit has a grass basket associated therewith for receiving and collecting grass clippings generated by operation of the cutting unit. Each grass basket has a forward portion of a bottom wall thereof formed by a piece of flexible material. An actuator is operatively engaged with the flexible material piece for lifting a front end of the flexible material piece upwardly relative to a rear end of the flexible material piece in response to changes in orientation between the cutting unit and the grass basket during operation of the mower to incline the flexible material piece and thereby promote the flow of grass clippings down the so inclined flexible material piece to more fully fill the grass basket.
