A growing chamber adapted to grow at least a portion of a plurality of plants therein, an inlet duct leading into the growing chamber, an outlet duct leading out from the growing chamber, the growing chamber being sealed from its surroundings except for the inlet and the outlet. A method of growing at least a portion of the plants in the growing chamber, can include :raising the relative humidity level in the growing chamber to at least 45 %, lowering the relative humidity level in the growing chamber to below 45%, and repeating the steps of raising and lowering at least five times during 9 single day.
