PROBLEM TO BE SOLVED: To reduce labor for watering and effectively utilize water resource without using a special device or a separately positioned water supplying tank by allowing a planting base arranged below culture soil to have water storage function and water discharging function such that the culture soil does not spill when using the culture soil when greening roof top and culturing flowers and ornamental plants.SOLUTION: The planting base constituted of a soil support on which the culture soil planted with plants is mounted and a water storage tank storing water is constituted such that a dam is arranged in the lower surface of the soil support, a water draining hole is arranged at an end part of the dam, a water draining hole is also arranged at an upper part of an outer peripheral wall surface of the water storage tank, water injected from an upper surface of the soil supported passes through a lower part of the dam arranged in the soil support and overflows from a water flowing out part arranged in an upper part of the side wall of the water storage tank, and water stored in the water storage tank is moved to the culture soil by a capillary water supplying mechanism.
