To provide a method for controlling the artificial lightening in cultivation of chrysanthemums by which noctuids can be controlled and the flowering can be suppressed.

Yellow lamps La comprising plural yellow fluorescent lamps are arranged at a regular interval parallel to a ridge surface for planting chrysanthemums and each yellow lamp La is lit so as to provide ≥36 lux illuminance of a position at about 1.2m which is at least the average height of a growing point of the chrysanthemums from the ground surface during a period for performing the suppression of the flowering thereof. In this case, the height, interval and number of the yellow lamps La are set so that the yellow lamps La may be lit at 100% rating with a dimming lighting device LC to afford the illuminance. In the period for providing only controlling effects, the brightness of each yellow lamp La is dimmed and controlled with the dimming lighting device LC and set so as to keep the illuminance at about 1.2m height within the range of 1 to 4 lux.