The invention relates to a greenhouse light, which comprises a light frame (1), a light source (2) fitted in connection with a first end of the light frame (1), and a reflector (3) arranged at a distance from the light source (2) for reflecting the electromagnetic radiation emitted by the light source (2). The light frame (1) of the greenhouse light is arranged to be turnable in relation to the reflector (3), so that the distance between the light source (2) and the reflector (3) can be adjusted. The invention further relates to a greenhouse light system and a method for altering the radiation pattern of a greenhouse light.