How Do I Raise the Relative Humidity in a Room?

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Things You'll Need

  • Humidifier

  • Plastic spray bottle

  • Shallow container

  • Stones

Spray houseplants to raise the humidity.

Relative humidity, or RH, is the amount of moisture in the air relative to the air's temperature. It is measured in percentage and according to the website Weather Prediction, relative humidity below 40 percent is considered dry, while relative humidity over 80 percent is considered moist. Raising the relative humidity in a space is crucial if there are any plants inside that thrive in moist conditions.


Step 1

Install a humidifier in the room. Humidifiers, available in both warm and cool air models, increase the relative humidity inside the room by releasing moisture into the air. Choose a humidifier suited for the room's size.

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Step 2

Turn down the heat inside the room. Heat evaporates moisture, lowering the room's relative humidity.


Step 3

Spray a mist of cool water from a plastic spray bottle in the room several times throughout the day. The liquid will help increase the relative humidity. Spray any plants found inside the room to raise the humidity as well.

Step 4

Fill a shallow container half full with cool water. Spread a layer of stones on top of the water. The water will evaporate slowly throughout the day, raising the room's relative humidity. Use the tray as a plant holder to provide extra moisture.


Install a hygrometer inside the room. This device measure the room’s relative temperature, allowing you to determine which techniques are most beneficial. The hygrometer will also ensure you are not raising the relative humidity in the room too high, which can lead to mold and mildew growth.



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