Abstract: A planter box for mounting on the top of a partial height wall partition having substantially vertical panels connected to a partition wall frame, the planter having a planting chamber defined by a wall connected to a bottom and at least one downwardly depending support flange for orienting and supporting the planter box on the upper horizontal surface of the partial height wall partition. The at least one downwardly depending support flange is concealedly secured between the substantially vertical panels and the partition wall frame and are spaced from the peripheral edge of the bottom so that the front surface of the planter box is substantially contiguous and flush with the front surface of the substantially vertical panels. Two downwardly depending support flanges in orthogonal relationship to one another can be provided for securement behind the two corresponding orthogonally opposed panels on the corner portion of a partial height wall partition.