How to Measure Houseplant Humidity Levels

Learn how to measure the humidity in your indoor garden with a hygrometer. Sufficient humidity is crucial for lush, healthy growth in your houseplants.

Understanding Houseplant Humidity Needs

Many houseplants come from jungle floors, meaning they thrive in high humidity. The challenge is that most homes range from 40% to 60% humidity. While 60% isn’t too bad, 40% is on the dry side. Some humidity-loving plants, like maidenhair fern, won’t do well in such dry conditions.

What is Humidity?

Humidity refers to the amount of water vapor present in the air. Relative humidity is the percentage of moisture in the air at a specific location, considering the maximum amount of moisture that air can hold before the vapor condenses into fog or rain. For example, a reading of 50% humidity indicates that the air contains half of the moisture it can hold before it condenses and becomes visible.

How Humidity Relates to Air Temperature

The amount of water the air can hold is directly related to the air temperature. Warm air can hold more moisture, which is why tropical areas are often high in humidity even when it’s not raining. For instance, air at 75°F with 50% humidity holds more moisture than air at 52°F with the same humidity percentage. This is an ideal scenario for houseplants, as warmer air with moderate humidity supports healthy plant growth.

Humidity for Houseplants Varies by Region

If you live in a dry, hot area of the U.S., such as the Southwest, your indoor air is likely to be dry. Conversely, regions with more humidity, like the Deep South, naturally have higher indoor humidity levels. Weather also affects humidity. Moist, rainy days increase humidity, while dry, windy days can lead to lower indoor humidity levels. Given that many houseplants require high humidity—some much more than others—it’s beneficial to measure the humidity level in your home. This helps determine if you need to increase the humidity in your indoor garden.

Using a Hygrometer to Measure Humidity

A hygrometer (also known as a humidistat) is an instrument used to accurately measure the humidity level in your home. Hygrometers can be found at some nurseries, hardware stores, and online. Modern hygrometers are digital and battery-operated, providing temperature and humidity readings with an error margin of 1 to 3%, depending on the product’s quality. These portable devices can be placed throughout the house to gauge humidity levels in various areas. When testing, ensure you get an overall representative reading by measuring the air in the room and right near the plant. After moving the hygrometer, allow it at least an hour to register the new temperature and humidity level. Keywords: how to measure houseplant humidity, how to measure humidity indoors, indoor humidity, measure humidity, use a hygrometer, how to use a hygrometer, hygrometer.