A plant cultivation method that comprises promoting the growth of a plant by microwave radiation. In a preset timing after a seed or bulb under cultivation germinates and shoots, the shoot or seedling is radiated with microwave for a preset period of time. In the microwave radiation to the germinating shoot or seedling, it is preferred to appropriately control the output and radiation time of the microwave so as to avoid heating of the radiation target by the microwave. For example, the output of the microwave is controlled to preferably 50 W or less, more preferably 30 W or less, and the radiation time thereof is controlled to preferably 120 minutes or shorter, more preferably 90 minutes or shorter. According to this treatment, the switch timing from the vegetative growth stage to the reproductive growth stage can be put forward and the growth condition of the plant in the vegetative growth stage can be improved in an environment that is disadvantageous for plant growth.
