Humidity is the amount of water in the air. Relative humidity is the amount of water in the air compared to the maximum amount of water the air can hold at that temperature. In cutting propagation, humidity can be important to prevent cuttings from wilting because cuttings have limited ability to take up water from the medium before they root.

Systems designed to maintain high humidity include poly tents and fog systems.

Photo showing a fog system.

Photo showing a poly tent system.