Abstract: In order to allow a watering operation to take place in a stable manner and in an automatic manner to allow an amount of water as needed with growth of a plant, there is provided a plant cultivating method in which plant is cultivated in a plant cultivating flooring member 1 accommodated in a plant cultivating vessel P1 accommodated in a water reservoir vessel P2 reserving water W therein. In the method, the plant cultivating vessel P1 is constructed such that this vessel when accommodating the plant cultivating flooring member 1 therein can float on the water and the vessel includes a water inlet hole 2 formed in a bottom B thereof so as to allow intrusion of water from the outside to the inside thereof under the floating condition.