Different types of house plants have different humidity requirements, but many common species require about 60 percent humidity. Proper humidity levels, along with proper light, soil and water conditions, contribute to the health of the plant. Because plants have an internal humidity level of nearly 100 percent, the plant is constantly evaporating water to the atmosphere, according to the Garden Line website. The drier the atmosphere, the more rapidly the plant will lose water.
Typical house plants thrive at a relative humidity of about 60 percent. Tropical plants often do best at a humidity of nearly 90 percent. This high a humidity level can be difficult to maintain in a house. Succulents, cacti and related plants usually require a humidity of about 30 percent. This level of humidity is below what is normally considered comfortable in a house.
Plants exposed to excess humidity often develop fungal diseases or mildew on their leaves or stems. These symptoms can be treated with improved ventilation and reductions in humidity. Plants in an environment with too little humidity can show dry leaf tips and new leaves. Dry plants sometimes lose their flower buds or drop the flowers shortly after opening.
High Humidity Plans
The high humidity level needed by a tropical plant make placement in the bathroom, the dampest room in the house, best, according to the University of Vermont Extension office. Other options for increasing humidity include double potting and pebble trays. Double potting involves placing a small pot or pots inside a larger pot that has been filled with peat moss. Keep the peat moss wet and allow the evaporation to create extra humidity around the plants. Pebble trays are a tray or pan filled with stones or pebbles that support the plant pots. Fill the tray with water to a level just below the bottoms of the pots.
Keeping humidity-loving plants grouped together helps them maintain their own climate with the proper humidity. In addition, plant owners can mist the plants to increase moisture on the plant, although this can also increase the possibility of fungus growth on the plant. A general rule of thumb, according to the University of Vermont Extension office, is that the lower the plant's light requirements, the higher its humidity needs.
Low Humidity Plans
Plants such as cactus requiring dry air should be kept in the driest part of the house. This is usually in areas removed from bathrooms and kitchens. A dehumidifier, a device that removes moisture from the air, can also be used to create a less humid environment for the plants.