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Gardeners often speak half-jokingly of their work in the garden as their therapy and health regimen. But it’s no joke – horticulture has long been an adjunct therapy prescribed for treatment of emotional and physical ills. Its healing value has been attributed to enjoyable and productive physical activity, contact with nature, and creative expression. And now, intriguing new insights come from discoveries in microbiology, as well.

Horticultural therapy through history

  • Physicians in ancient Egypt prescribed time in a garden for treatment of mental disorders. In the Middle Ages, monastery hospitals would have gardens both for growing medicinal herbs and for the healing influence of time spent with natural beauty and green things.
  • Benjamin Rush is often credited as the father of horticultural therapy in North America. He was a doctor who signed the Declaration of Independence and later became an influential proponent of medicinal gardens and of the healing benefits of horticultural activity. The term “horticultural therapy” was coined by FC Menninger, whose Kansas hospital founded in 1919 promoted gardening as a therapy for patients with mental disorders.
  • There have been degree programs and professional organizations dedicated to horticultural therapy since the 1970s in Canada and the US. Horticulture has been offered for prison rehabilitation and for the treatment of schizophrenia, depression, PTSD, autism, Alzheimer’s, and addictions.
  • Here in Edmonton, the Alberta Edmonton Hospital has offered a horticultural therapy program that has treated over a thousand psychiatric patients since 1999.

Microbiology and the garden

  • In the late 19th century, discovery of the role of “germs” in infections resulted in improved hygiene, and this combined with the advent of antibiotics greatly improved life expectancies and transformed both medical practice and everyday habits of housekeeping and self-care. But in making our environments more sterile, we may have gone too far, and in recent years we have seen a course corrective.
  • More attention has been paid to the microbiomes in soil and in the human body, and beneficial effects of microbes in our environment have been explored and revealed. Studies have suggested that children who spend time outdoors and (who live in less-than-sterile homes with pets) develop more robust immune systems due to multiple exposures to low doses of diverse microbes.
  • Mycobacterium vaccae is a bacterium found in soil and known to have immune-boosting activity. Oral doses given experimentally to cancer patients did not ameliorate their cancer, but did help to relieve their depression and anxiety. vaccae caused an immune response in mice that stimulated production of the naturally occurring feel-good brain chemical, serotonin.
  • It has been suggested that gardeners and others who spend much time in nature could benefit physiologically from the cumulative effect of many small doses of vaccae. They may experience an antidepressant effect that boosts the feeling of well-being and reduces anxiety.


Be happy, dig in the dirt


Gardening provides many benefits that redound to physical and mental health: time spent outdoors and attuned to nature, creative expression, self-sufficiency and food.  The gardener’s habit of paying attention to small things becomes a meditation. And quite possibly, the gardener absorbs some friendly “germs” along the way that may sustain health and emotional well-being at the physiological level.