A mower deck includes at least one cutting chamber with a spindle-mounted rotary cutting blade. The cutting chamber includes an upper wall and an outer extent bounded at least partially by a side wall. The side wall presents a discharge opening. A cut-off baffle extends between the spindle and the outer extent of the cutting chamber. The cut-off baffle adjusts between an open position in which the discharge opening is at least partially unobstructed and a closed position in which more of the discharge opening is obstructed. A spreader plate lies over the upper corner of the cutting chamber near the discharge opening. The spreader plate adjusts between a first retracted position spaced away from the discharge opening and a second extended position closer to the discharge opening. The cut-off baffle and the spreader plate may be adjusted to control the discharge of grass clippings from the cutting chamber.
