Roof Greening If only planted with goldmoss sedum or a usable green land a vast number of roof landscapes can be turned into blooming gardens. A green roof is an ecologic and economic alternative to conventional roofs. The garden of extension. Roof and walls do not have to be gray unused spaces. Flat and slanting roofs of garages or residences can be greened easily and thus become specious green biospheres. The planting supports a balanced indoor climate: cool in summer, warm in winter. The exterior walls of a house will also stay dry.