Abstract: A cultivation plant comprising several separate water accumulators (1) which are buried under a ground area (5) in which plants are to be grown, and which water accumulators are formed as a closed container (11) which is filled with a porous, water-soaking substrate (13) which opens to the ground to be irrigated over openings (12) at the top or at the side of the water accumulator (1). Each water accumulator is separately connected to a central force for supply of water and for supply of air. When using the cultivation plant water is supplied to the porous, water-soaking substrate (13) until the substrate has reached a predetermined maximum degree of moisture, whereafter the water supply is ceased, whereas air is supplied to the substrate (13) at a pressure which is slightly higher than the static pressure of the substrate, so that the air is forced through the substrate and out into the irrigated ground for oxygenating same.