Smelling Roses, Lowering Cortisol

Tomorrow, celebrate the Third Annual National Public Gardens Day, a national day of celebration to “raise awareness of America’s public gardens and their important role in promoting environmental stewardship and awareness, plant and water conservation, and education in communities nationwide,” according to the American Public Gardens Association (APGA).

As the world’s cities grow and concrete jungles expand, public gardens are going to become more and more important for human health.

Currently, the world is undergoing what the United Nations Population Fund (UNFPA) calls “the largest wave of urban growth in history.” The agency notes that in 2008, for the first time in history, more than half of the world’s population is living in towns and cities. This number will reach almost 5 billion by the year 2030, with the greatest concentration of urban growth in Africa and Asia.

And, according to CNN chief medical correspondent Sanjay Gupta, we should “expect it to get worse.”

During a November 20 CNN segment about urbanization and health, Gupta noted that the near-constant sensory stimulation that bombards most urban dwellers can cause spikes in cortisol, also known as the “stress hormone.”

As a result, it can be difficult for the brain to hold things in memory. High concentrations of cortisol can “reduce your self-control, dull your thinking…it may even speed up cognitive decline, just from living in a city,” says Gupta. “Think of it as your brain more rapidly aging.” And there you have it: Living in cities is hazardous to your health. In a word: unnatural.

In this sense, “natural” means green. Gupta noted that “recent studies have shown just glimpses of green areas will make huge differences to your overall cognitive function. It makes you less distracted, less stressed and more relaxed.” So the key is to “find green spaces in your city and make sure to use them as much as possible.” Urban dwellers, it seems, can help keep their brain function healthy just by looking at plant life. And flowers in particular seem to do the brain good.

As noted an earlier post, Jeannette Haviland-Jones, director of the Human Development Lab at Rutgers University, said that “flowers have immediate and long-term positive effects on reactions, mood, social behaviors and even memory for both males and females,” a finding of her study “An Environmental Approach to Positive Emotion: Flowers,” published in the journal Evolutionary Psychology .

So tomorrow, do your brain a favor and take some time out to take a stroll through a public garden. And once in while, stop to smell the roses.


  • Find a public garden near you (Don’t forget to check the weather.)
  • Sign the Fair Flowers for Human Rights petition
  • Take a free wildlfower walk at Wave Hill (May 10-13, New York City)
  • Create a cut flower garden
  • Search for organic flower growers on
  • Donate to the Millennium Seed Bank
  • Analyze and reduce your impact on the environment with the National Grid Floe
  • Follow 13.7 Billion Years on Twitter