African Violets in better days-- Historical photo
People grow house plants for many reasons. Plants add color, beauty, and interest to home and offices. Just looking around those spaces — and gardening centers!– reveals that growing plants is an activity that many enjoy. In a recent Master Gardener class, I was reminded of another fascinating fact to keep in mind about indoor gardening: house plants clean the air.
The contribution of house plants for cleaning indoor air was explored in the landmark 1989 NASA Clean Air Study, a collaboration between NASA and the Associated Landscape Contractors of America. Most of us are well aware of the fact that plants absorb carbon dioxide and release oxygen, which forms a symbiotic relationship with humans since our breathing does the opposite. The NASA Clean Air Study found that plants also eliminate significant amounts of benzene, formaldehyde and trichloroethylene from the air. This two-year study suggested that plants might provide a natural way for dealing with “sick building syndrome.” Some of the most effective plants included English Ivy (Hedera helix), Spider plant (Chlorophytum comosum), Peace Lily (Spathiphyllum ‘Mauna Loa’), Chinese Evergreen (Aglaonema modestum), Bamboo Palm (Chamaedorea seifritzii), Snake plant (Sansevieria laurentii), Heartleaf philodendron (Philodendron oxycardium,) and several plants in the Dracaena family, including Janet Craig, Marginata, and Mass cane/Corn Plant. Pot Mum (Chrysantheium morifolium) and Gerbera Daisy (Gerbera jamesonii) were also found to be effective air cleaning plants. Further details about individual plants’ specific toxic removal qualities can be found here. The study concluded with the suggestion that 15 – 18 house plants in 6-8 inch container sizes would improve the air quality in an average 1,800 square foot home.
Ironically, our house plant population is at an all-time low. A quick inventory reveals one huge Norfolk Island Pine and several offspring in a big pot (which must be re-potted this spring!), two African violets (one thriving, one surviving), one pot of thyme on the rebound from a near-death experience, and one cup with basil seeds germinating on the windowsill. That’s a grand total of 5 indoor plants– a far cry from the 15-18 needed to filter our indoor air effectively. I’ll be making a concerted effort to expand our indoor plants. Any suggestions?
How many house plants share your home? Does knowing that house plant can improve indoor air quality motivate you to grow them? What plants have you grown successfully? What are your reasons for gardening indoors?
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