Abstract: A grass dethatching system includes a frame with at least one support member suitable to support the frame above the grass, the frame is adapted for mounting a dethatching apparatus, and the frame is adapted for detachably attaching to a vehicle. The dethatching apparatus includes a dethatch assembly rotatable about a central axis and at least one elongate member rotatable with the dethatch assembly at a location offset from the central axis. A plurality of tines are freely rotatably connected to and spaced apart along the elongate member in such a manner that the tines will periodically contact the grass when the dethatch assembly is rotated about the central axis. A drive assembly is connected to the frame which rotates the dethatch assembly at a rotational speed independent of the motion of the support member.