Friday, January 7, 2011

Clean Air Houseplants

Hello again,

The cold of winter keeps us indoors more than other times of year and quite often more than we would like!

Following is an excerpt from that discusses how effective many popular houseplants can be. The list concludes with a "Top 15" list. We may not always have the exact matches at Skillin's but we have plants from all the families listed and any plants in those families will show the same clean air attributes.

Here is the excerpt:

"In the late 1980s, a study by NASA and the Associated Landscape Contractors of America (ALCA) resulted in excellent news for homeowners and office workers everywhere. The study concluded that common houseplants such as bamboo palms and spider plants not only make indoor spaces more attractive, they also help to purify the air!

The study was conducted by Dr. B.C. Wolverton, Anne Johnson, and Keith Bounds in 1989. While it was originally intended to find ways to purify the air for extended stays in orbiting space stations, the study proved to have implications on Earth as well.

Newer homes and buildings, designed for energy efficiency, are often tightly sealed to avoid energy loss from heating and air conditioning systems. Moreover, synthetic building materials used in modern construction have been found to produce potential pollutants that remain trapped in these unventilated buildings.

The trapped pollutants result in what is often called the Sick Building Syndrome. With our ultra modern homes and offices that are virtually sealed off from the outside environment, this study is just as important now as when it was first published.

While it’s a well known fact that plants convert carbon dioxide into oxygen through photosynthesis, the NASA/ALCA study showed that many houseplants also remove harmful elements such as trichloroethylene, benzene, and formaldehyde from the air.

NASA and ALCA spent two years testing 19 different common houseplants for their ability to remove these common pollutants from the air. Of the 19 plants they studied, 17 are considered true houseplants, and two, gerbera daisies and chrysanthemums, are more commonly used indoors as seasonal decorations.

The advantage that houseplants have over other plants is that they are adapted to tropical areas where they grow beneath dense tropical canopies and must survive in areas of low light. These plants are thus ultra-efficient at capturing light, which also means that they must be very efficient in processing the gasses necessary for photosynthesis. Because of this fact, they have greater potential to absorb other gases, including potentially harmful ones.

After conducting the study, NASA and ALCA came up with a list of the most effective plants for treating indoor air pollution.

The recommended plants can be found below. Note that all the plants in the list are easily available from your local nursery.

1. Philodendron scandens `oxycardium', heartleaf philodendron
2. Philodendron domesticum, elephant ear philodendron
3. Dracaena fragrans `Massangeana', cornstalk dracaena
4. Hedera helix, English ivy
5. Chlorophytum comosum, spider plant
6. Dracaena deremensis `Janet Craig', Janet Craig dracaena
7. Dracaena deremensis `Warneckii', Warneck dracaena
8. Ficus benjamina, weeping fig
9. Epipiremnum aureum, golden pothos
10. Spathiphyllum `Mauna Loa', peace lily
11. Philodendron selloum, selloum philodendron
12. Aglaonema modestum, Chinese evergreen
13. Chamaedorea sefritzii, bamboo or reed palm
14. Sansevieria trifasciata, snake plant
15. Dracaena marginata , red-edged dracaena

For an average home of under 2,000 square feet, the study recommends using at least fifteen samples of a good variety of these common houseplants to help improve air quality. They also recommend that the plants be grown in six inch containers or larger.

Check out the entire link at It is a good clean read!

Update: At about the same time we were publishing this post, gardening friend Paul Parent sent out an article about Clean Air Houseplants in his weekly gardening email. I recommend you sign up for his weekly email at! Here is an excerpt of what Paul had to say about Clean Air Houseplants:

"NASA has done extensive research on the efficacy of plants at absorbing contaminants in the air, while converting carbon dioxide into oxygen. We're going to take a look at some of the plants that provide indoor pollution relief. By incorporating these plants into your home, you will be improving the quality of the air that you breathe. These plants can also be easily moved outdoors; imagine a spring afternoon on your front porch, surrounded by the very plants that offered so much pleasure inside throughout the colder months.

Philodendrons were determined by NASA to be among the best house plants for removing toxins from the air. They love temps from 60 to 72 degrees, and do not require a lot of light. Occasionally treat them to a "bath" of soapy water to remove dust and control insects. When the temps turn warm, bring them outdoors, placing them in shade, of course always ensuring that their feet rest in rich, moist soil containing a good supply of organic matter. Well-rooted plants should receive diluted applications of a liquid fertilizer every week or two.

Ferns, which in the language of flowers mean sincerity, magic, fascination, confidence, and shelter, have a lot in common with dinosaurs. They co-existed in the Mesozoic era, and even predate dinosaurs. Dating back 300 million years, they are among the world's oldest living things. Perennials, they can be either evergreen or deciduous. They dislike strong sunlight, high wind, and dryness at the root zone. They range in size from the wall-rue at 2" to the tree ferns of New Zealand that reach heights of 30', so astute gardeners will be able to find the perfect fern for their needs.

Consider incorporating Boston ferns in your clean-air indoor garden; they are full and lush and work equally well in pots or hanging baskets. As the maiden-hair fern thrives on high humidity, it's the perfect choice for placement in a bathroom. Just remember to keep your ferns in indirect light, whether inside or out, and place their containers in pebble-filled trays, adding water into the tray until it just covers the pebbles; do not over-water.

In the language of flowers, the spider plant represents an offer of elopement. An amazingly easy-to-care-for plant, it takes a lot of effort to kill the "airplane plant." It has proven quite effective in the absorption of chemicals that include formaldehyde, xylene, benzene, and carbon monoxide. It likes medium to bright light, isn't fussy about excess humidity, and prefers cool to average temps, while tolerating warmer conditions.

Another indoor plant that does equally well outside when the weather warms up, it's perfect for a hanging basket. This fast-grower sends out "babies", or spiderettes which are plantlets on long stalks. To propagate set the plantlet, while still attached to the mother plant, on the surface of a pot filled with a soilless potting medium, using a bent paper clip to hold it in place. Once it begins to root, sever it from the mother plant. If plantlets on your spider have already begun to develop roots, simply sever and pot them in soil. One mother plant can lead to many other plants!

Golden pothos, aka devil's ivy, is practically impossible to kill. It will grow under nearly any conditions, either as a climber when trained around a wooden stake, or in a hanging basket. You have probably seen it trailing along the perimeter of office cubicles, where it thrives with only fluorescent lighting. Another of our favorite air purifiers, it removes formaldehyde from the atmosphere, and sets the standard for neglect-tolerant plants. In fact, about the only thing that will kill a pothos is over-watering; a shallow root system makes it susceptible to root rot. This in a way is somewhat ironic, as your home can sport a plethora of pothos by simply placing clippings in water, and in about a week roots will begin to form. When a plant is fully rooted, pop into a pot of loose, well-draining soil, and keep it evenly moist.

We've started you out with some of the most reliable houseplants that will not only provide you with healthier air, but are also easily moved outside during warm weather. Now it's up to you to exploit these easy-to-grow beauties so that you may find yourself forever surrounded by a garden. "

Mike Skillin
Skillin's Greenhouses
January 7, 2011

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