Gardeners have solid research to defend the urge to buy more houseplants. A study from NASA and the ALCA (Associated Landscape Contractors of America) concludes that houseplants purify the air.
We all love to have houseplants like bamboo palm and spider plants to make our rooms look warmer and more inviting. This study, which was intended to purify air for astronauts orbiting in space, proved to have positive implications on Earth, too . The study was conducted in 1989 by B.C. Wolverton, Anne Johnson, and Keith Bounds.
Today’s new construction is built to be more energy efficient and tightly sealed. This prevents both hot and cold air from getting indoors and makes our HVAC systems more efficient. In addition, building materials used today are more man-made. These man-made materials often have harmful chemicals in them that can off-gas long after construction is over. Tighter seals and more chemicals have caused indoor air quality to decline according to the EPA. In addition, we are spending more time indoor. These two factors combined mean that we need to take steps to improve indoor air quality.
The problem with indoor air quality is so serious that there is even an illness that has arisen called called Sick Building Syndrome. The symptoms are dizziness, headache, throat irritation and asthma.
We’ve all heard that plants convert carbon dioxide into oxygen. That’s not all they do. The study also revealed that plants also remove harmful elements from the air like formaldehyde, trichloroethylene and benzene.
For two years NASA and ALCA tested 19 houseplants that are commonly grown to see whether they could remove chemical pollutants from the air. Out of these 19 plants, 17 are classified as houseplants and 2 are more seasonal decorations, gerbera daisy and chrysanthemum.
You might wonder why these plants do such a good job of absorbing chemicals. By nature indoor plants have adapted to survive in lower light. They are more efficient at capturing light. This also means they are more efficient in processing gasses for photosynthesis. By default they are also more efficient at absorbing the potential harmful gasses in our homes.
The three big offenders in the NASA study were Formaldehyde, Benzene, and Trichloroethylene. Surprisingly these are all used in many common building products. Benzene is used in oil paints, which are almost always used to paint wood. Trichloroethylene is used paint, adhesive and varnish. Formaldehyde is used in particle board and insulation.
You might be wondering if some plants are more effective than others at improving air quality. They answer is yes, but all of the plants listed below improve air quality.
Some plants are even better at removing specific chemicals.
- If you have a Benzene problem, you should grow english ivy, gerbera daisy, mums, peace lily, bamboo palm and Mother-In-law’s tongue.
- If you have a Trichloroethylene problem you should grow peace lily, gerbera daisy, and bamboo palm.
- If you have a Formaldehyde problem you should grow bamboo palm, Mother-in-law’s tongue, dracaena warneckei, peace lily, dracaena marginata, golden pathos, and green spide
The top recommended plants for improving air quality are listed below. All of these should be widely available at your local nursury.
1. Philodendron scandens `oxycardium’, heartleaf philodendron. This is one of the most common and reliable houseplants. It does well in medium intensity light but can grow in low light. Keep out of direct sun. They need to be misted regularly and dusted to keep the leaves clean. Soil should be moist but not wet. Allow to dry between watering.
2. Philodendron domesticum, elephant ear philodendron. The elephant ear philodendron requires a fairly large pot. It should not be placed in direct sun, keep in indirect light. Grows will with humidity. It grows well if you put rocks in the bottom of the watering saucer so the roots don’t stay wet.
3. Dracaena fragrans `Massangeana’, cornstalk dracaena. This plant grows well in low light. They tend to be very forgiving of missed waterings and deglect. They can grow to as large as 12 feet, but typically around 6 feet. The leaves are poisonous to pets.
4. Hedera helix, English ivy. Ivy needs plenty of light, but it can grow with artificial light. It does best when it is watered well and then allowed to dry.
5. Chlorophytum comosum, spider plant. When it’s growing this plant should be watered only occasionally. It requires moisture during the spring and summer.
6. Dracaena deremensis `Janet Craig’, Janet Craig dracaena. This plant should be potted in a container with a hole and placed in a saucer with pebbles. Just add water the the tray.
7. Dracaena deremensis `Warneckii’, Warneck dracaena. The Warneckii should be kept away from doors and windows that are opened often. It does well away from any type of draft, including air vents. The soil for this plant needs even moisture and it’s best not to leave water in the saucer. It can grow to six feet tall. Moderate indirect light is best.
8. Ficus benjamina, weeping fig. This is the most popular indoor tree. It’s best to water the ficus with filtered water because it is very sensitive to chemicals in water. Once you place your ficus, don’t move it. These plants like stability. Keep the plant in an area that is not drafty. Be careful not to overwater. Misting the leaves works well.
9. Epipiremnum aureum, golden pothos. Golden Pothos also like areas that are not drafty with bright indirect light. Pothos do well as hanging plants, but they don’t grow as large without a totem pole. Keep the soil evenly moist but not too wet.
10. Spathiphyllum `Mauna Loa’, peace lily. Peace lilies like even moisture and temperatures above 55 degrees. If they start to wilt, try repotting in a larger container. They grow best in bright, indirect light.
11. Philodendron selloum, selloum philodendron. This plant grows well in bright, indirect light. Due to its tropical nature, it likes moist soil. Don’t oversaturate the soil, but don’t let it get dry.
12. Aglaonema modestum, Chinese evergreen. These are one of the easiest houseplants to grow. They don’t require much direct light. They like warm conditions, over 65 degrees. These plants like to be watered thoroughly and then left to dry out before they are watered again.
13. Chamaedorea sefritzii, bamboo or red palm. This plant will also grow in low light conditions. They do best when you repot them in a larger container right after you get them. These plants like even moisture and do best with filtered water.
14. Sansevieria trifasciata, snake plant. This plant is also called the Mother-in-law’s Tongue. It is a good plant for beginners. It likes dry soil and grow well in bright or low light.
15. Dracaena marginata , red-edged dracaena. Red-edged dracaena like bright indirect light. They need to be watered whenever the surface soil is dry, but don’t allow them to sit in water.
How many plants do you need to make a difference in your indoor air quality? Approximately 15 plants in 6 inch pots or larger will make a difference in a 2,000 square foot home. You can multiply or divide based on the size of your home or apartment.
If you want to watch a video of a regular person who did an experiment that measures the indoor air quality in their home after buying just 3 plants just watch this video.
To read more about the NASA indoor air study see this article.
What houseplants to you like to grow in your home? Let us know and send photos.