Low humidity isn’t a great place to be either. To ensure our climate is in good form and optimal for our plants, we often need to supplement humidity, specifically in Vegetation and/or when ambient humidity levels are too low. To low a humidity or to high a humidity level will negatively affect your plants ability for optimal transpiration, the means in which our plant leaves breathe. Need more humidity? Need to keep a tight VPD? A humidifier is what you need.