What is the ideal relative humidity range for most plants?

The ideal relative humidity range for most plants is typically between 40% and 60%. This range provides a suitable environment for healthy plant growth and development. Within this humidity level, plants can effectively perform essential processes such as transpiration and photosynthesis.

Transpiration, the process of water movement through a plant and its evaporation from aerial parts, primarily leaves, is crucial for nutrient uptake and temperature regulation. At 40% to 60% humidity, moisture loss is balanced, allowing plants to maintain turgor pressure without excessive water loss, which could lead to stress and health issues.

Lower humidity levels can cause increased transpiration rates, leading to water stress, while higher humidity levels can result in fungal issues and various plant diseases due to insufficient air circulation and moisture retention. Hence, the 40% to 60% range is often recommended in both indoor gardening and greenhouse management, making it the most favorable for the majority of plant species.