Issue: September 21, 2002

Houseplants for indoor air pollution

Do you have a list of houseplants that produce the most oxygen and are the best plants for improving the indoor air?

It is difficult to answer your question regarding oxygen. The answer will be dependent on the health of the plant, its size, and the light levels where it is growing. In general, more light means more photosynthesis and more oxygen production. However, some plants such as tropical foliage plants are better adapted to low light conditions and therefore best for increasing indoor oxygen levels. Plants not as well adapted to shade will tend to deplete the oxygen because they will be respiring (releasing carbon dioxide) as well as photosynthesizing (producing oxygen). Whether or not they are net producers or consumers depends on the light level and shade adaptability of the plants. If the light conditions are very low, philodendron and other plants like it will produce more oxygen. In brighter light, other plants will do better. Most home conditions are such that the period of bright light is very limited, thus limiting maximum photosynthesis. Your question is difficult to answer without knowing your light conditions - intensity and duration.

It is easier to answer the question about general indoor air quality. About 20 years ago, NASA published some research identifying which plants are best at removing pollutants from the air. Even here, the best plant varied depending on what pollutant was of concern. Spiderplant (genus Chlorophytum) was best at removing gaseous pollutants such as formaldehyde. Plants with fuzzy leaves were best at removing particulate pollutants such as smoke and grease particles.

Houseplant prep for winter

Is it too early to worry about bringing plants indoors for the winter? - Tommy W., Santa Fe

Now is the time to begin preparing to bring plants indoors for the winter. I wouldn't call it worrying, however. Begin inspecting plants for signs of disease or insects. If there are problems, you have time to begin treating with whatever means you choose, depending on the problem. In some cases, it may be best not to bring infested plants indoors. Once indoors, pests and diseases may become very difficult to control and begin spreading to other, otherwise healthy plants. Prevention is the best choice.

Now is also a good time to begin propagating overgrown plants so that the space required during the winter is minimized. Many houseplants are easily propagated by means of cuttings to produce smaller plants. Some plants, such as begonias and impatiens, may be propagated by simply putting cuttings into a glass of water until roots form. The cuttings of other plants should be started in potting soil. But, now is the time to begin the process.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!