Abstract: Method and lighting device for providing artificial light optimally to plants is achieved effectively by moving both the lighting device (2, 3 and 4) and its emission pattern to maximize incident light on the plants (5, 6 and 7) being cultivated. The horticultural lighting device illuminates plants so that the lighting device is moved vertically and at least one light emitter (3 and 4) and/or reflector (2) is rotated to maximize light exposure from the lighting device on the plants (5, 6 and 7). In the best mode the movable and rotatable lighting device is used to grow very high plants. The lighting device (2, 3 and 4) is moved by a motor programmed to change the position of the lighting device and the orientation of the emission pattern in accordance with the growth cycle of the plants in the greenhouse (350) to maximize incident flux on the plants.