Humidity Requirements for Houseplants
University of Wisconsin
Humidity is one of the environmental factors you should consider in the care of indoor plants. If humidity is too high, plants become susceptible to rot, mold and mildew. This is rarely a problem in homes, but if it is, you can control it with increased ventilation.
If the relative humidity is too low, plants may lose water faster through the tiny openings in their leaves than they can replace it through their roots. Characteristic symptoms of this are browning leaf tips, yellow leaf margins, bud drop, shriveling and wilting. This is often a problem for indoor plants, especially during winter, when indoor temperatures are raised, and the air is dry.
There are several ways to minimize the problem of low humidity in homes:
- Water plants carefully whenever they need moisture. Don't water by the calendar.
- A good soil mix that holds water, plus temperatures that are relatively cool can help to overcome the negative effects of low humidity.
- Install humidifiers in individual rooms or in heating systems if possible.
- Keep plants away from radiators and drafty locations. Moving air picks up water vapor.
- Place plants on a tray of wet pebbles. The water evaporates upward from the surface of the stones, creating a more humid micro-climate around the plants. The pots MUST sit above the water line. Placing a small saucer beneath each plant will insure this.
- Group plants together so they can benefit from moisture that evaporates from each-other.
- Place plants in areas that are naturally higher in humidity; for example, near the kitchen sink, above an aquarium, or in the bathroom, provided they still receive enough light.
- Put especially sensitive plants in terrariums, where you can control the environment more easily. But keep terrariums out of direct sunlight or plants will "cook."
- Grow plants that are well adapted to dry air; for example, cacti, succulents, and plants with leathery or firm leaves.
For more information contact your Extension Service county office.
Reviewed 2009.
