Disclosed is a cultivation method for illuminating plants at night or in a lightless environment. For the illumination, the exit light has an emission peak wavelength in the green to red region and flashes with a flashing pattern of prescribed light period duration and dark period duration. For the flashing, the duty cycle given by formula (1) is 50% or less. Duty (%) = period duration/(light period duration + dark period duration) x 100 (1) Provided is a cultivation method that controls the blooming of short-day plants such as chrysanthemums while providing insect-screening effects such as mothproofing.
