Humidity
The amount of water vapour in the atmosphere, measured on a scale of relative humidity (RH), from 0% (totally dry air) to 100% (saturated air), at any given temperature. Most species grow satisfactorily within the range of 56-80% RH. Below 65%, growth is progressively and adversely affected. Above 80%, there are increasing problems with fungal and bacterial diseases, and above 90%, transpiration is restricted, which affects the movement of some nutrients, particularly calcium, within the plant, and may result in deficiency symptoms.