The Homeowners Column

The Homeowners Column

Houseplants as air filters

Photo of Sandra Mason

Sandra Mason
Extension Educator, Horticulture
slmason@illinois.edu

Every few weeks we have a revolving discussion in our office about the attributes of real versus fake plants. Ok I will admit living breathing plants need periodic tending, weekly watering and maybe picking off a few dead leaves. Fake plants (also known as artificial botanicals) need as much care as a door stop and are about as exciting. Our real versus fake discussions always follow the obvious demise of some of our office plants. Any plants outside of my observable orbit languish in the twilight zone common in many offices along with other unclaimed tasks such as making coffee or putting paper in the copy machine.

Besides the relaxing, refreshing nature of real plants there may be other excellent reasons to

bring the outdoors in. Over the years as offices and homes have become better insulated and windows better sealed the concern for indoor air quality has risen. Formaldehyde, a volatile organic compound (VOC), emitted from plywood, carpet, particle board, tobacco smoke and some adhesives can be a major indoor air contaminant especially in new construction. Houseplants may be one way to help improve the air we breathe.

In an article published in the October 2010 issue of HortScience Journal of the American Society of Horticultural Science researchers reported on a study of the formaldehyde removal capabilities of a diverse cross section of plants including ferns, woody and herbaceous foliage plants and herbs.

Of 86 plants tested, ferns were the hardest working plants in formaldehyde removal. In fact, seven of the top nine performers were ferns including Japanese royal fern, Osmunda japonica; Brake fern, Pteris multifida; Frog's foot fern, Polypodium formosanum; and Hare's foot fern, Davallia mariesii.

The other great filterers in this study were lavender, geraniums and rosemary. Of the more traditional houseplants giant dumbcane, lady palm, rubber tree and flamingo flower rated high in air filtering; however, all plants tested showed some ability to remove formaldehyde.

Formaldehyde removal did not increase dramatically with higher light intensities; however, the removal was five times faster in light than in dark. In winter, plants will grow better with supplemental fluorescent lighting and the additional light will help them to work longer at cleaning the air.

Researchers have also found that formaldehyde removal is not just up to the plants. Soil microorganisms inhabiting healthy potting soil are also involved in removing formaldehyde and other toxins from the air day and night.

Ok, ferns may be the best air filters but they are not the easiest plants to keep alive indoors. Ferns need regular watering and will suffer leaf drop if allowed to dry even once. Boston ferns will probably take the most neglect. The low humidity of winter homes is tough on ferns and us. To raise the humidity around plants use a humidifier or group plants together. Plants can be kept on a tray of wet pebbles or sand. Misting plants does little to increase humidity unless done continually throughout the day.

Chinese evergreen, aglaonema, snake plant, dracaena, philodendron and pothos are some of the toughest houseplants to survive low light and little water. Do some homework to discover which plants will survive your style of care or your style of neglect.

So the next time someone suggests swapping artificial botanicals for living, breathing plants remember fake plants can only collect dust and real plants can improve the air and our attitude.

View Article Archive >>