A greening system us disclosed for enabling plants/vegetation to grow only with natural rainfall, without any particular irrigation facilities, enabling a full-blown garden to be constructed on building rooftops, minimizing the applicable loads on the building, and free from the risk of leakage. Planting container 1 comprises box 2 with stickers 3 to carry perforated partition panel 4. The lower half of the container is constituted as water storage 5, and drain holes 6 are opened on sides of the container. Soil layer 7 placed on partition panel 4 is formed of light woody soil-based on charcoal 9 and humus timber chips for absorbing moisture transported from the water 8 stored in water storage 5 by evaporation or difference in humidity, to have a large water capacity letting less water evaporate into the air. Charcoal 9 absorbs water from the air inside the lower half of the container to water the plants. Water storage 5 assures an amount of water necessary for plants to grow.