Plants Humidity refers to the amount of moisture in the air.
Some plants are sensitive to low humidity.
Most common house plants, given an otherwise favorable environment, will not be injured by humidity levels found in most homes. Humidity levels will fluctuate during the year. When the furnace is on in winter, the air will be drier. This will be the time when sensitive plants show low humidity injury. Low humidity means plants lose more water and may need more water in winter.