Abstract: A mulching blade for a gasoline- or electrically-powered rotary lawn mower having a housing, which blade is mounted on the shaft of the lawn mower motor below the deck of the housing. The blade has a central mounting area and inner and outer sections sharpened on their leading edges which extend radially from the mounting area. The outer section cuts the unmowed grass. All sections are pitched upwardly away from the direction of rotation of the blade to lift the clippings as they are cut by the outer section and to turbulently suspend the clippings within the housing while the inner sections re-cut them repeatedly, comminuting the clippings into a fine mulch which falls by gravity to the soil level under the grass. Preferably there are three inner sections which jointly form an arch between the mounting area and the outer section and act as a comminuting tubulator.