A process and combination for improving the growth of plants and preventing the plant support medium from retaining too great a quantity of water. A foraminous body is placed in the bottom of the container and prior to the time it is placed therein, it is perforated to form cylindrical conduits vertically completely through the foraminous body wherein the perforations are about 1-5 mm in diameter and are spaced apart about 1-8 mm. Soil is placed on top of the foraminous body, a plant is germinated or planted, watered and fertilized to grow in the container. The water will be retained in the sponge-like foraminous body around the conduits and be available to the plant roots. The conduits themselves will be free of water and will provide a reservoir of oxygen for the roots.