A plant growing box with four inwardly and upwardly sloping side walls defining a quadrilateral enclosure, held together by four readily separable corner brackets having a removable securing pin. The meeting edges at the corners are spaced apart from each other to provide for ventilation there. Preferably the box walls slope inwardly at about 15.degree. to vertical, and they are each supplied with an exterior control handle. Two lower edges provide a bottom-receiving slide for a removable perforated bottom.