Amid the noisy coverage of high-cost health care and high-tech medicine, one inexpensive, low-tech therapy has received scant attention—horticultural therapy. This approach has proven an effective adjunct therapy for a broad range of conditions: mental illness, disabilities, AIDS, autism, orthopedic recovery, brain injuries, substance abuse, depression, cancer, Alzheimer’s, attention deficit disorder, obesity and burn victims.

This is no revolutionary therapy. In ancient Greece, the first healing places were gardens surrounded by rows of sleeping rooms where the sick would rest after tending to the plants and bathing in nearby streams. Set on farms, these early wellness gardens gave patients fresh vegetables and afforded them slow physical movements among colorful flowers.

Later these became spa-gardens where advanced healers such as Hippocrates, the western world’s first doctor, extended care further with fresh medicinal herbs and even dream interpretation. He also insisted that the aristocracies in the local towns and cities allow rooms for both rich and poor—a paradise on earth. No wonder gardens were the first hospitals.

In the USA, Benjamin Rush, the country’s first surgeon general and a pioneer in the treatment of mental illness, was convinced that gardening speeded the recovery of asylum patients. Currently, there are more than 500 healing gardens at U.S. health facilities, and the number, you might say, will only grow.

Gardens represent a fresh horizon. The garden awakens all of the senses: visual, tactile, olfactory, kinesthetic. In tending a plant, a person is engaged with daylight, fresh air, water, earth, the seasons, the rising and setting of the sun—reconnected to the natural world.

Plants are egalitarian partners, providing a sense of purpose, self-reliance and accomplishment. As one tends the plant, the plant responds. Every bit of love is reflected in the plant’s health, beauty and productivity.

If this sounds touchy-feely, well, it most wonderfully is. But the fuzzy feelings inspired by horticulture are bolstered by a growing body of scientific research. The researchers’ findings substantiate green therapy’s extraordinary health benefits.

Thanks to biofeedback measurements, researchers know that, within minutes of stepping into a garden, a person experiences positive changes in stress level, heart rate, blood pressure, and body temperature. Work with plants over time, confers enhanced mood, improved coordination, and reduced pain awareness. Hippocrates reborn!

How can you explain these extraordinary results? Richard Mattson, Professor of Horticultural Therapy at Kansas State, was a pioneer in the field. He cites three factors. The first is that over a few hundred million years, man co-evolved with plants developing a dynamic mutual relationship.

The second factor is nurturing, an activity ingrained in who we are. The will and ability to bring a plant (or child) to life, nurture it into growth, and help it survive is an indispensable human endowment. In nurturing, we ourselves are nurtured.

The third factor he confesses, “…drives people a little crazy.”

Plants radiate what he terms a “halo effect”. The stored energy within the plant—the union of sunlight, air, and minerals is felt and absorbed by humans. Just as we absorb the stored energy of plants we eat, we absorb energy interacting with them.

Skeptics may scoff at such notions of plant energy and demand the data. But I feel sure that most home gardeners and patients engaged in plant therapy have first-hand knowledge of this “halo effect”—the glow when you grow.

Curious? Embark on an experiment in your own laboratory: your back yard.

A version of this article appeared in The Clarion-Ledger and The Sacramento Bee.