Keep plants away from cold drafts, radiators, and hot air vents. Also make sure houseplant foliage doesn't touch cold windows. Many houseplants prefer a humidity level of 40-50 percent. Humidifiers are an excellent way to increase the relative humidity in a home. Simple cultural procedures can also increase the relative humidity around houseplants.
Group plants together.
The water evaporating from the soil, plus water lost through the plants, will increase the humidity in the immediate vicinity of the plants. Another method is to place the plants on trays filled with gravel and water. The bottoms of the pots should be above the water level. Misting houseplants is not an effective method to raise relative humidity. Misting would have to be done several times daily and is simply not practical.