A convertible mower deck (10) has a plurality of adjoining cutting chambers (11, 12, 13) under a mower deck (10), each cutting chamber (11, 12, 13) having a cutting blade (21, 22, 23) mounted to the lower end of a vertical spindle. Angled pivoting baffles (41, 42) are positioned in the openings between adjoining cutting chambers (11, 12, 13), and a baffle also is mounted in the discharge opening from one of the cutting chambers (13). The baffles (41, 42, 71, 73) may pivot between an open position for the grass clippings to be discharged or collected, a closed position for the grass clippings to be mulched, and one or more intermediate positions for some of the clippings to be discharged or collected, and the remainder to be mulched.
