SummaryAn account is given of the distributions of heat and relative humidity from three methods of orchard heating, together with the results of experiments with a simple type of humidified heating. Ignited balls of papier mache which had been soaked in crude oil, were humidified with saturated garden refuse, such as long grass or lawn clippings. This arrangement heats the air, and at the same time either maintains or enhances the relative humidity. No lowering of the internal temperature of the bud is produced, and the method helps to control a frost at its source, by diminishing radiation of heat from the earth to an open sky. Frosts may therefore be controlled in practice by the expenditure of about one‐third the fuel used in the flame‐type heaters.Lateral distribution of heat from orchard heaters is not great. Suggestions are made for the alternate disposition of fruit trees and heaters upon a slope. Advantage may thereby be taken of the katabatic wind which occurs during a radiation frost, to direct the heated air towards the tr