PROBLEM TO BE SOLVED: To simplify vegetational greening of a base by previously carrying out vegetation in a post-planting care upland field, germinating plants from seeds previously scattered in vegetational mats of a prescribed thickness made of a nonwoven fabric or a felt, laminating a plurality of layers of the vegetational mats and laying the laminate when greening work is performed in a tilted base having a prescribed gradient such as the rooftop, a roof or a terrace of a building, etc. SOLUTION: This greening system is designed to naturally carry out water flowing actions and not to cause a phenomenon such as root rot of vegetations 7 by water holding properties of the vegetational mat 2 in the lowermost layer. When the gradient of the base 1 is steep, a system having water supply functions with a water sprinkling type sprinkler, etc., is additionally installed to keep the water supply actions. A presser 6 such as a cover, for example pressing gravel is laid on the surface of the vegetational mat 2' in the topmost layer.
