A method for increasing the yield of a flowering plant includes positioning a lighting device with respect to a lower minor height of the flowering plant, i.e., at a height of less than half of the plant's total height. The method includes irradiating the lower minor height of the plant with light in a predetermined range of the electromagnetic spectrum for a duration of a flowering stage of a life cycle of the flowering plant. The lighting device may be an annular clamshell design that circumscribes a stalk of the flowering plant. Such a design may be clamped to the stalk via a spring force of a pair of spring-loaded clamps. The lighting device may include a plurality of ref LEDs arranged in an arcuate manner. At least 80 percent of the light from the lighting device is in the predetermined range of 580 nm to 780 nm, and may be in the range of 600 nm to 700 nm.