PROBLEM TO BE SOLVED: To provide a method for reducing equipment cost and immediately protecting plants from disasters.SOLUTION: A plant is hydroponically cultivated outdoors with stems and leaves projecting to the upper surface of a cultivation box while roots of the plant is held within the cultivation box made of an insulating material by feeding/discharging a culture solution to the roots of the plant inside the box. If a disaster approaches the cultivated plant, the cultivation box is inverted upside down to form a plant protection space under the cultivation box as a roof, and the stems and leaves of the plant are located within the protection space to protect the plant from the disaster. This method for protecting the plant hydroponically cultivated outdoors from the disaster is provided.
