Abstract: Method and apparatus for controlling the temperature in greenhouses, the nominal value of the temperature being adjusted between a higher daytime temperature and a lower night temperature. In order that the plants in the greenhouse shall not be exposed to a shocklike reduction of the total energy supply to the plants if a considerable sunlight energy quantity has been supplied to the plants in the daytime, the nominal value of the night temperature is controlled in dependence of the sunlight energy quantity received by the plants, in such a manner that the night temperature is adjusted to a higher value at a higher sunlight energy quantity.