When Hanan Brown got stressed at work, he would treat himself to houseplants. “At one point, I think I had more than a hundred plants,” said Brown, who lived in a studio apartment and was working on the front lines of the pandemic in Boston, “but it never looked messy or felt like much.” For Brown, indoor plants were A lifeline for dealing with the pressures of medical training during a pandemic Surrounding himself with lush greenery has always calmed him, he said, and helped him feel rejuvenated.
Why indoor plants make you feel better, according to science
“Different characteristics of plants, such as their look, smell, and feel, affect us in many ways,” said Mingming Gu, associate professor of horticultural sciences at Texas A&M University. “They can feel good when touched, make the space more fragrant and pleasing to our eyes.”
But how and why do plants have such positive effects on us? Here’s a look at research over the past few decades showing how houseplants affect our mental and physical health.
People and plants are naturally related. Humans have an inherent relationship to plants and other organisms, according to what’s known as the biophilia hypothesis, an idea popularized in 1984 by naturalist and writer E. O. Wilson. Since then, more than three decades of worldwide research has confirmed the hypothesis and shown that natural environments have a significant effect on increasing positive emotions and decreasing negative ones.
“When people profess the commonly held belief that being in nature relaxes them, helps them recover from stress and tragedy, and that being in nature is a healing process, we now know there is a strong foundation for this,” Wilson said in 2015. Interview with The Washington Post.
And as people started spending more time indoors, we brought in parts of the natural world to continue to feel connected.
Plants can quickly improve mood. Our connection to plants is so strong that sometimes it only takes a few minutes of being in their presence to start feeling better. Studies have found that as little as 20 minutes is enough to make us feel more at peace. In one experiment, participants who spent even five to 10 minutes in a room with a few houseplants felt happier and more satisfied than those in a room without plants. In another study, participants felt more calm and positive after spending 15 minutes in a room close to a tall plant (about five feet) compared to other objects.
However, Joe reminds us that “not only does the sight of a plant improve our mood so quickly, but the scents can make a huge difference as well,” though studies on the effects of plants on the non-visual senses are limited.
Plants bring relief indoors. If you’re stuck in an office or other small space for hours at a time, plants can bring about feelings of escape. In a study conducted during stay-at-home orders due to the pandemic, participants with indoor plants experienced significantly fewer symptoms of depression and anxiety than those who didn’t. Being surrounded by houseplants caused them to feel “disconnected” from social or material demands.
Plants can reduce stress. Other studies have shown that interacting with plants suppresses the system in our bodies that is activated when we feel signals of distress. Young adults in one study who spent a few minutes repotting and transplanting an indoor plant reported feeling less stressed at the end of the task than peers who participated in a computer-based activity. Additionally, blood pressure measurements were significantly lower among the subjects who handled the plants, suggesting that the plants have the ability to dampen the body’s fight-or-flight response.
Plants can recharge us. “Plants also have tremendous repairing power,” said Melinda Knuth, assistant professor of horticultural sciences at North Carolina State University. “Whether it’s outdoors like on a patio or indoors with houseplants, nature can help us feel recharged and grounded.”
When we focus on demanding activities for a long time, such as our jobs, it can lead to mental exhaustion and negative feelings that can affect how well we are able to pay attention. Seeing a plant in this state can provide a spark of interest, reorient our attention, and restore our depleted mental and physical resources, an idea known as attention restoration theory. Studies have found that the plant’s “restoring” effect has a wide range: renewing positive emotions, increasing productivity, creativity, and the ability to pay attention.
A data-driven guide to investing in houseplants
How do you choose which houseplants to buy? Research can provide some practical guidance:
number of plants: Although there is no magic number, having five or more plants showing foliage can increase positive feelings. For example, in one study, participants in a room with bamboo palms, Chinese evergreen trees, and heart-leaf philodendrons (five in total) felt more carefree and friendly compared to those in rooms without plants. Alternatively, a tall potted plant (about five feet) or three or more small floral displays (such as sweet peas, larkspurs, or forest sage) can elicit similar positive reactions.
color: The greener, the better? In a study using English ivy, yellowish green and bright green leaves increased feelings of euphoria and relaxation, while bleached green leaves stimulated mostly negative emotions. For flowering plants, a study found that purple, green, red, pink and white plants can lower people’s blood pressure and heart rate. However, purple and green flowers were most effective in relaxing the body, reducing anxiety, and improving mood. Another study found that red and yellow roses elicit a more calming response than white roses.
real vs artificial: Indoors, having any type of greens—including pictures of plants—is better than none at all. However, real plants have a greater mood, alertness, and relaxation effect than artificial plants. The same applies to real flowers versus artificial flowers. In a study of high school students, participants who looked at real pansies for three minutes felt more comfortable than those looking at artificial lilies. Gu’s point about mood influences beyond visual cues may help explain these findings.
placement: Although there is little research on this topic, some studies suggest that having plants closer than 10 feet to a person has a positive effect on mood. A study conducted by Knuth, North Carolina, showed that most people place houseplants in living rooms, bedrooms, and sometimes even kitchens. As working from home expands, placing plants in home offices or other work areas can be beneficial.
It’s important to remember the caveats in many of these studies: Some were conducted in highly controlled settings, primarily among college students. They reflect snapshots of time rather than long-term effects. And their real-world effects on a more diverse group of people—for example, among the elderly or those in low-resource settings—may be different. But it’s hard to ignore the amount of research showing houseplants to have a huge positive impact on mood and physical health. So, when we find ourselves spending more time indoors—whether due to the pandemic, work, or the weather—maybe it’s time to pick up some houseplants.
Lala Tanmoy Das is an MD student in New York City doing research in molecular cardiology. Find him on Twitter: @tweet.
