Twenty-two case studies were included in a meta-analysis of the effects of gardening on human health in children and adults. Inclusion criteria for the initial literature search consisted of studies collecting data on people's health outcomes related to gardening, published in peer-reviewed journals since 2001, and written in English. Studies focusing on home gardening, community gardening, and horticultural therapeutic gardening were included. This initial search yielded 79 articles. Further selection criteria for the meta-analysis included (1) quantitative as opposed to qualitative surveys, (2) a focus on outdoor gardening, (3) comparison of control and treatment groups (e.g., non-gardeners and gardeners), (4) reported group size and health outcomes of both groups, and (5) having more than 11 participants in each group.
The 22 studies included in the meta-analysis reported 76 comparisons between control and treatment groups. Most of the studies came from the United States, followed by Europe, Asia, and the Middle East. The studies reported a wide range of physical, mental, and social health outcomes, including reductions in depression, anxiety, and body mass index and increases in life satisfaction, quality of life, and sense of community. Positive associations between gardening and health outcome were significant for all subjects and for sets of subgroup studies.
The demographic characteristics of the participants and settings included in the meta-analyses varied widely across the studies, and findings showed that the benefits experienced by some subgroups were greater than the benefits experienced by other groups. Patients and people engaged in horticultural therapy tended to experience the greatest benefits. Subgroup analyses also indicated that the well-being benefits of gardening were more sharply enhanced than the physical health benefits. This may be due to subjective measurements used for wellbeing assessments showing immediate results, while objective physical health outcomes usually aren't immediately evident.
This meta-analysis provides a quantitative synthesis of evidence relating gardening to human health benefits. The overall results indicate that gardening can improve public health; and the evidence for this is robust. These findings support public investments in gardening opportunities for all kinds of people, including children. Such investments could help alleviate some of the health inequalities in our society.
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