The invention relates to a flexible polyurethane foam comprising viable and/or germinated plant seeds. The flexible polyurethane foam may comprise a reinforcing fabric composed of fibers, for example synthetic-polymer fibers or rottable natural fibers. The flexible polyurethane foam may further comprise a substance having high water-holding capacity, for example a polyacrylate-based superabsorbent. By way of plant seeds the flexible polyurethane foam may comprise seeds of grasses, mosses, lichens, ferns, fungi, aquatic plants, flowering plants and perennial woody plants. The flexible polyurethane foam is obtained by mixing (a) polyisocyanates with (b) at least one comparatively high molecular weight compound having at least two reactive hydrogen atoms, (c) optionally low molecular weight chain-extending agents and/or crosslinking agents, (d) catalysts, (e) blowing agents, (f) optionally other added-substance materials and (g) plant seeds and reacting the mixture to form the flexible polyurethane foam. To vegetate areas, the flexible polyurethane foam in the form of a finite or continuous sheet is laid on the area or firmly bonded thereto and irrigated. This permits vegetation of exteriors, roof areas, rocky soils, sound-absorbing barriers and desert floors. A flexible polyurethane foam comprising viable and/or germinated lawn seed can be used as rolled sod.
