By Dr. James Feucht, Colorado State University Cooperative Extension Landscape Plants Specialist
Houseplants are Coloradans' answer to a green environment, especially during the six-month period each year when Mother Nature colors the outdoors brown.
Two difficulties in cultivating some tropical house-plants are Colorado's low humidity and intense sunlight.
The forced-air furnace means rough going for some houseplants. Warm air moving through the system loses almost all of moisture, reducing humidity even more than outdoors.
You can solve some of these problems. Locate plants to provide correct light and temperature exposures. Consider adding a power humidifier to your furnace or placing a portable humidifier near the houseplants.
Try locating specific types of plants in different exposures. This will depend upon the location of windows in your home. Don't place plants directly on window sills, particularly if the windows are finished with terrazzo. Cold conducted from the outside will keep the soil so cool that the plants will do poorly. A table located away from the windows is a better location.
During the winter, the sun is lower in the sky. The intensity of sunlight coming through glass can be extremely high, putting a greater demand on houseplants for moisture.
Ideal for most common houseplants, such as splitleaf philodendron, monstera, wandering Jew and dumbcane, is an east exposure with indirect sunlight. The best location for indirect light is near a light-colored (preferably white) wall that will reflect sunlight.
Warmer, south exposures are best for cacti, succulents and some flowering plants, such as geranium. These plants must have sun and their succulent nature will tolerate hotter, brighter exposures. With the exception of geraniums, these plants are not likely to need any more water than those in other locations of the house.
West exposures will be hotter and drier, thus succulents and geraniums will do well here, too. Some flowering begonias will do well in west windows because they tolerate brighter light. It will be helpful if they can be lightly screened from direct sun, such as with lace curtains.
Avoid placing some flowering plants in north exposures; few will flower with reduced light. Among the better plants are figs, including rubber plants and fiddle-leaf fig, English ivy, spider plant, peperomia, Chinese evergreen and the familiar mother-in-law's tongue (sanserveria). Jade also will tolerate relatively low light, but this plant is a succulent and seems to thrive in most locations. It might, however, sunburn in an extreme south exposure.
African violets are best in an east exposure. They usually do well, but during the winter, they may need supplemental light. They may not flower without longer days.
Watering -- how much and how often -- is a common question. Usually houseplants are overwatered or watered too little, too often. Water houseplants thoroughly so soil is saturated. To avoid buildup of soluble salts, discard water that accumulates in drip pans.
With the exception of ferns, coleus and a few others that require frequent watering, it is best to let the plants become a bit dry before watering again. This slows plant growth during winter months, reduces plants' needs and compensates for lower humidity.
For more information about care of houseplants, contact your local office of Colorado State University Cooperative Extension.
Photograph courtesy of Judy Sedbrook.
© CSU/Denver County Extension Master Gardener 2010
888 E. Iliff Avenue, Denver, CO 80210
Date last revised: 01/05/2010