How to Increase the Humidity in a Terrarium

Terrariums function like small greenhouses.

A terrarium is essentially a miniature greenhouse. Its walls are transparent glass or plastic, allowing sunlight in while a sealed top helps the terrarium maintain a humid environment. While high humidity is necessary in a terrarium, overwatering is a common mistake that causes disease and injury to plants. Add water to the terrarium only when the soil feels dry. In a properly maintained terrarium, this might be as seldom as once or twice a year.

Things You'll Need

• Gravel
• Moss

Instructions

1. Check the lid to make sure it fits tightly. An ill-fitting lid allows moisture to escape and disrupts the terrarium environment.

2. Place a shallow dish of water in the terrarium. The water will evaporate, adding to the "rain cycle" of the terrarium. When the humidity has equalized, remove the dish.

3. Move the terrarium out of bright sunlight that might be overheating the interior and causing low humidity. Supplement with fluorescent lights to give plants adequate light without added heat.

Tips & Warnings

• If mold is growing inside the terrarium, remove the lid and allow it to air out for 15 minutes. Do not leave the lid off of the terrarium for long periods of time.

References

• University of California: Terrariums
• University of Florida: Terrariums
• University of Arizona: Interior Plants: Selection and Care
• University of Georgia: Growing African Violets