Houseplants need humidity

Cold weather means that most folks have their homes closed up and the heat
on. After a while, the lack of moisture in the air becomes quite noticeable
to the occupants, especially the houseplants. For those plants that prefer a
high level of humidity, the low humidity commonly found in homes in winter can
be a shedding experience as their foliage yellows, dries up, and falls off.

Houseplants do best at a relative humidity of 70 to 80 percent, a level that
is often difficult to maintain in the home. Any increase in humidity will help
plants, however, especially if the dwelling is heated by a wood or coal stove
or fireplace.

One way to help increase the humidity around plants and keep them healthy and
growing is to use humidifiers when available and practical. It’s also important
to avoid raising the air temperature too high. With a given amount of water
in the air, the higher the air temperature, the lower the relative humidity.

An inexpensive way to raise the humidity is to place pans of water on stoves
or radiators to act as humidifiers. A gravel-filled tray partially filled with
water also works well. Just place your potted plants on top of the gravel. The
humidity will be increased in the immediate area of the plants. But do not allow
the bottom of the pot to come in contact with water as this can lead to a waterlogged
soil ball that could kill the plant.

Move humidity-loving plants to the kitchen or bathroom. These rooms usually
have higher humidity than the rest of the house. Or make a grouping of plants.
This will form a microclimate with a higher humidity. And keep plants, especially
ferns, away from wood stoves, fireplaces, and heat registers.

Many people mist their plants. This is okay, but avoid prolonged misting. A
film of water on the foliage is often all that various fungus spores need to

A general rule of thumb to follow if you don’t know the humidity requirements
of a plant is that the lower the light requirement, the higher the humidity

Dr. Leonard Perry is Extension Professor, Department of Plant and
Soil Science at the University of Vermont. Visit his website at