Successful gardening in the greenhouse decisively depends on the correct ration of climate and light. The light quantity may seem to be sufficient on the outside, but inside the greenhouse, it is often too dark during spring and autumn time. Specific growth-promoting lights are therefore necessary for the gardener to work successfully during the poorly lit seasons of the year. However, these lights are also most suitable for box bay windows, aquariums, and hydroponic cultures. Specific HQL mercury-vapor lamps generate a light spectrum, which is very similar to sunlight. Strong, but harmless due to the lowest radiant heat. They are additionally energy-saving and are characterized by a long lifetime. Luminous intensity and light distribution are depending on the distance between lamp and plant. The larger the surface to be illuminated, i.e. the higher the lamp is hanging on top of the plant, the stronger the HQL lamp has to be. Two lamp powers are available. The light is TÜV-tested, 230 V, switchable from 80 to 125 watts. Including ballast and mercury-vapor lamp. Stable aluminum housing, painted in white. Ø18 cm, height 23 cm. One lamp is sufficient for a normal greenhouse.