An automatic plant watering device includes a thermoelectric module with a cold face that can be energized to drop its temperature below 32 degrees F. A condensation member is thermally connected to the cold face and has a wall exposed to ambient air for water vapor to condense on and freeze when the module is energized. A water collection chamber positioned below the exposed wall is configured to hold collected melt water from the exposed wall until a collected melt water temperature has risen above 32 F. A moisture sensor is used to initiate a chilling cycle controlled by a controller to energize the thermoelectric module for a period of time in excess of an hour to cause a build-up of frost on the exposed wall and thereafter to deenergize the thermoelectric module to permit the temperature of the exposed wall to rise above 32 degrees F.

A refrigeration cycle that is formed by connecting a compressor, a condenser, an expansion valve, and an evaporator and that performs cooling operation; an evaporator heating device that heats the evaporator; a drain pan that receives drain-water from the evaporator and drains the drain-water; a drain-pan heating device that heats the drain pan; a frost detecting device including a light-emitting element that emits light to the evaporator and a light-receiving element that receives reflected light from the evaporator and outputs a voltage according to the reflected light; and a control device that controls on-off operation of the evaporator heating device and the drain-pan heating device. The control device determines a frosting condition on the evaporator from an output of the frost detecting device and individually controls the evaporator heating device and the drain-pan heating device in accordance with the determination result.