Benefits of Houseplants Less Than Thought, But Still Considerable

old studies of plants' effects on air debunked

By Jonny Lupsha, Wondrium Staff Writer

Potted plants don’t actually improve the quality of indoor air, according to a new study published in Journal of Exposure Science & Environmental Epidemiology. Keeping houseplants has long been believed to provide many benefits, but improving air quality no longer appears to be one of them. However, there are still good reasons to keep plants in the house.

Woman watering potted house plants by window
New studies indicate that houseplants do not have as much of an effect on air quality as once thought. Photo by Taras Garkusha / Shutterstock

According to the study, potted plants have been known to remove VOCs—or volatile organic compounds—from the air in small chambers over the course of several hours or days. However, their benefits now seem to be less significant than originally thought, since previous studies offered results that were often “not directly applicable to contextualizing plants’ impacts on indoor VOC loads.” At the same time, having an indoor green thumb offers other benefits for the household that are worth considering. To get you started on maintaining a green thumb for indoor plants, let’s take a look at tips for planting an outdoor garden.

Picking Soil Type

When deciding to plant a garden, the first vital component is the soil.

“Soil is a complex mixture of minerals, organic material, water, and life,” said Professor Lonnie A. Gamble, Co-Director of the Sustainable Living Program at Maharishi University of Management. “We’re used to thinking of soil as a lifeless substrate for growing plants—we treat soil like dirt. Well, dirt is inert, but healthy soil is teeming with life; a single teaspoon of soil holds up to one billion bacteria, several yards of fungus filaments, several thousand protozoa, and scores of nematodes.”

Unpleasant as it sounds, when soil and organic matter pass through a worm’s digestive system, the nutrients in it break down just enough to be taken advantage of by the other components of the soil.

“Worm poop, or castings, is a mix of soil, beneficial microorganisms, and organic substances beneficial to plants,” Professor Gamble said. “They’re a great plant fertilizer and soil enhancer.”

In order to encourage worms to fertilize your soil and keep it healthy, Professor Gamble recommended keeping plenty of organic matter in the pot for them to eat, “preferably applied as surface mulch.” Worms love newspaper, he said, so you can recycle your newspapers in an outdoor garden.

Picking Plants

When it comes to choosing which plants to grow, the first distinction is between two types: “Annuals, which need to be planted from seed every year; and perennials, which are planted once and then provide a yield for many years,” Professor Gamble said. “There’s also a kind of hybrid: annuals that self-seed heavily and come back every year like perennials.”

For example, he said that most vegetables in the grocery store are annuals, while most fruits and nuts are perennials. If possible, growing them together in a “polyculture” can yield excellent results that cut down on costs and worry.

“Polycultures are groups of plants that have a synergistic effect when grown together,” Professor Gamble said. “For example, growing a nitrogen-fixing plant like clover along with wheat minimizes the need for nitrogen fertilizer. Perennial grains would allow grains to be grown in perennial polycultures, mimicking the prairie.”

Monocultures, or monoplants, may be simpler to keep track of but come with their own sets of difficulties. According to Professor Gamble, monocultures are more prone to problems with insects and disease.

Although recent studies have said that houseplants do not improve the indoor air quality of your home as much as once thought, caring for and maintaining the health of plants still offers a relaxing and rewarding pastime—and mastering outdoor gardening can lead to better success of keeping your houseplants healthy. Cultivating quality soil and choosing the right types of plants to select are important first steps on your way to becoming a capable botanist.

Professor Gamble is a founding faculty member and Co-Director of the Sustainable Living program at Maharishi University of Management

Professor Lonnie A. Gamble contributed to this article. Professor Gamble is a founding faculty member and Co-Director of the Sustainable Living program at Maharishi University of Management, where he has taught since 2003. He holds a Bachelor of Science degree in Electrical Engineering from North Carolina State University.