What is Humidity?
Humidity is the relative amount of water vapor contained in the air. As temperature rises the capacity of the air to hold water vapor increases.
It is measured on a scale of “relative humidity” ranging from 0% which is dry, to 100% that is completely saturated. Fog, for example, would indicate 100% relative humidity.
According to the Mayo Clinic, ideal humidity in your home is between 30% and 50%. Most common houseplants can thrive in those humidity levels, too. But what if you live in an apartment without control of your space's humidity levels—or have humidity sensitive plants that prefer 60% relative humidity or more? Below we’ll go over easy ways to increase your humidity levels for your houseplants.
Pro tip: The thinner and more papery the leaves are, the greater the likelihood of the plant needing higher humidity. Plants with thicker, waxier leaves (like most succulents) are better able to withstand dry air.
6 Ways to Boost Humidity for Houseplants
- Invest in a humidifier: Consider adding a tabletop humidifier to any space with your plants, or even a larger one that helps the humidity of the entire room if you have the space.
- Group plants with similar needs together: Place your plants together in the same space, close together, to create a micro-climate as they transpire water from their leaves.
- Use wet pebble trays under planters: These saucer or drip trays are filled with stones and water and meant to be placed underneath a planter to localize humidity more consistently around an individual plant.
- Add glass domes over smaller plants: Glass domes can be placed over your smaller plants to create humidity (think of a green house or conservatory), but make sure to remove it for a few hours a day to allow your plant to get airflow.
- Fine-mist, often: You can mist your plants with water, but will need to do so frequently. This method only increases humidity somewhat locally for a short period, and when it evaporates, the humidity goes back to what it was.
- Double pot your plants: You can double pot by placing a potted plant in a planter that is 2-3 inches larger in a diameter, then fill the sides with damp sphagnum moss.
Troubleshooting Humidity Levels
It’s important to find the right balance between low and high relative humidity. Some plants, like drought-tolerant succulents, prefer dry conditions and would not benefit from any of the tricks above. Look out for the symptoms below to help you find the right scenario for your plants.
If your plant has low humidity, symptoms can include:
- Shriveling or curling leaves
- Browning or crisping leaves
- Leaf scorch
- Wilting leaves and stems (if paired with wet soil, this symptom could be a sign of overwatering instead)
If your plant has too high humidity or a lack of airflow symptoms can include:
- Mold or mildew development on the plant, planter, or on top of the potting soil
- Fungal infections
- Overwatering symptoms like yellowing leaves (too much water vapor, moist soil, and little airflow prevents plants from drying out at a sufficient rate)