Top Ten Houseplants for Controlling Indoor Air Pollution

In recent years, more and more attention has been paid to indoor air pollution. Since the average American spends most of their time indoors, indoor air pollutants like VOCs, mold, and dust are taking precedence over car exhaust and smog. What can you do to control indoor air pollution in your home or office? Typical approaches are to buy an ionizer or air purifier in order to improve indoor air quality. However, findings by NASA show that common houseplants are excellent at absorbing toxins and pollutants from the air. They have proven so effective they may even be used in the future aboard space stations as part of the life support systems [1]. Which plants are the best choices for improving your indoor air quality? Environmental scientist and former NASA employee Bill Wolverton writes about the fifty top air purifying indoor plants in his book "How to Grow Fresh Air" [2]. Below are his ten top choices.

-- Arrowhead vine (Syngonium podophyllum): A lovely vining plant with green and yellow variegated leaves. The arrowhead vine likes medium light, high humidity, and soil with a lot of organic material.

-- Bamboo palm (Chamaedorea Seifrizii): This is a larger sized indoor plant; it can grow up to ten and twelve feet tall. They do best in medium light and high humidity.

-- Boston fern: These ferns have been used as houseplants since the Victorian era. Like all ferns, they don't like low humidity or high heat. However, make sure that they don't get wet feet - don't let the pot sit in standing water.

-- Draceana `Janet Craig': Draceanas like medium light and it's best to let them dry out between waterings. This variety grows to about a foot tall and has lovely dark green leaves.

-- English ivy (Hedera Helix): While it is better known for its use in outdoor landscaping, English ivy also works well as a house plant. This ivy does well in almost any indirect light, and can also adapt to artificial light conditions.

-- Ficus alii (Ficus macleilandii `Alii'): Rather than a small plant or shrub, this ficus is a tree than also grows well indoors. Because these plants are grown in large pots, you can allow the top two inches of soil to dry out rather than just the first half inch. Make sure that your ficus gets plenty of indirect light.

-- Golden pothos (Epipremnum aureum): Also known as devil's ivy, this indoor plant is a low vining plant that can grow up to ten feet long. I've seen them trained along walls or string so that they grow all the way across a room! This is one of the easiest indoor plants to grow, and one of the most entertaining.

-- Peace lily (Spathiphyllum): Peace Lilies are good at improving indoor air quality not only because they remove toxins from the air, but also because they give off more oxygen than other indoor plants. Because they are tropical plants, they like high humidity and to be watered twice a week

-- Rubber plant (Ficus `Robusta'): This variety of ficus is one of the easiest indoor plants to keep happy. Rubber plants like medium light, moderate moisture and humidity, and normal indoor room temperatures.

-- Spider plant (Chlorophytum comosum `Vittatum'): Only complete abandonment will kill a spider plant. Spider plants are also very easy to propagate: once they get large enough, they will send out runners with tiny spider plants at the end. Cut one off and put it in its own pot: voila, you have a new spider plant!

If you don't see your favorite indoor plant here, never fear: all indoor plants are good at cleaning up the air. You can easily make up for the lower effectiveness of these plants by having more of them around your home or your office.

For maximum air cleaning efficiency, keep your plants in good condition. Pay attention their light and moisture preferences. In all cases, houseplants prefer diffused light rather than direct light. The best light is one that does not warm your hand, but still casts a shadow. When watering, make sure not to over or under water. Don't let plants dry out completely. If the soil is dry a half inch down into the soil, it is time to water.

Most houseplants like moderate to high humidity, which is easy to maintain. Make sure not to place them in front of air vents, as the constant air flow will dry out your plants quickly. You can also group plants together, mist them regularly, or place them in a tray filled with pebbles and water. With the last option, make sure the pot rests on the pebbles and not in the water. Leaving the soil soggy or in standing water can cause a plant to rot.

Finally, make sure to clean and repot your plants periodically. Plants are always growing, and will eventually need to be moved to a larger pot. You can tell it's time to repot if roots are beginning to grow out of the bottom of the pot or if water flows through the pot immediately upon watering. To clean your plants, use water mixed with a little organic dish soap. This will keep dust of the plant's leaves, making it easier for the plant to photosynthesize, and it will also help control common indoor plant pests.

[1] Plant-Care.com, 'Top 10 Plants Most Effective in Removing: Formaldehyde, Benzene, and Carbon Monoxide from Air', Plant-Care.com.

[2] Julie Bawden Davis, 'Indoor Plants Can Battle Pollution', San Fransisco Chronicle.