Box for cultivating plant

The combination of a building having a roof, a drainage pipe at the periphery of the roof and a roof-protective covering substantially entirely covering the roof and comprising a plurality of rectangular-shaped turf cultivating plant boxes which are installed on the roof contiguously laterally and longitudinally to form a grid,

• each said turf cultivating plant box comprising:
• (a) a rectangular bottom plate bounded by four side walls,
• (b) a first hollow ridge extending longitudinally entirely across the box between a first opposed pair of said side walls and having a central portion substantially equidistantly spaced from the side walls of said first opposed pair of side walls,
• (c) a second hollow ridge extending laterally entirely across the box between a second opposed pair of said side walls and having a central portion substantially equidistantly spaced from the side walls of said second opposed pair of side walls,
• (d) the first and second hollow ridges being constituted of elevated portions of said bottom plate, the ridges each having an upper extremity which is of lesser elevation than the side walls,
• (e) the central portion of the first hollow ridge and the central portion of the second hollow ridge integrally merging at right angles,
• (f) a multiplicity of water drainage perforations formed through each of the first and second ridges at regular intervals at the upper extremity thereof,
• (g) the underside of each of the first and second ridges defining water drainage grooves communicating with said multiplicity of perforations and opening at each end through a respective wall of said respective opposed pair of walls between which said respective ridge extends, the groove defined by the first ridge and the groove defined by the second ridge communicating with each other at said integrally merged central portions, said openings of said water drainage grooves being aligned and in communication with the openings of the water drainage grooves formed in a plurality of turf cultivating plant boxes which are laterally and longitudinally contiguous with said cultivating plant box to form continuous lateral and longitudinal water drainage channels,
• (h) each of said boxes being filled to a level above said ridges with soil for cultivating turf, and
• (i) natural turf planted on said soil.