Abstract: A plant protector is positionable about the base of a young tree or other plant. The protector has first and second shells, each formed of a rigid material and having a semi-cylindrical shaped portion and with flanges extending outwardly from and running longitudinally along the semi-cylindrical portions. Each semi-cylindrical portion may have raised circumferential ribs which are spaced apart at regular intervals to increase strength and rigidity. The opposed flanges abut and the semi-cylindrical portions form a cylindrical tube when the shells are engaged together. The shells are locked together by locking structures formed on at least one of the flanges of the shells. The shells may be held together at one edge by a hinge extending longitudinally along edges of the shells. Various locking structures may be used, such as mating bosses and indentations formed on the flanges on opposite sides of the first and second shells.