Table 2.

Details of observational studies

Study	Program Setting	Design	Participants	Female%	Mean age	Groups	Measures	Duration	Outcome
Christina and Shannon (2005)	Virginia (USA)	Cohort Studies	48 elderly people with dementia recruited in rural southwest Virginia	45.83	80, SD=±11.0	Gardening group and traditional activities group	Levels of engagement, MMSE	9 week × 1 × 30 min	HT activities promote participation and motivation in production activities compared to traditional activity groups
Park et al. (2009)	Manhattan (USA)	Cohort Studies	Recruited from the community including 11 active gardeners, 14 gardeners and 28 non-gardeners	64.15	71.94, SD=±7.81	Active gardeners,gardeners and Non-gardeners	BMI, own health assessment , hand function, BMD	—	There were no differences between the three groups in mental health or bone density, but leap gardeners and gardeners had greater hand and grip strength than non-gardeners.
Chen and Janke (2012)	Michigan (US)	Cohort Studies	1,585 gardeners and 1,652 non-gardeners from the Health and Retirement Study and the Consumption and activity mail survey	53	74.20, SD=±7.09	Gardeners and Non-gardeners	Balance, gait, falls and chronic disease incidence	—	Gardeners had significantly better balance and gait speed and less chronic disease and dysfunction than non-gardeners.
Lêng and Wang (2016)	TaiWan (China)	Cohort Studies	3,547 gardeners and 1,029 non-gardeners including a national sample of older adults and 50-year-olds from Taiwan	46.6	66.6, SD=±9.37	Gardeners and Non-gardeners	Risk of death, socioeconomic status, health behaviors and conditions, depression, activity limitations, and comorbidities	8.8, SD=±3.4years	Daily home gardening was associated with high survival rates, with significant effects for those with activity limitations and no effect for those without mobility restrictions who were not depressed
Machida (2019)	Japan	Cross-sectional study	500 gardeners and 500 non-gardeners recruited from the community	30.6	63.6, SD=±2.6	Gardeners and Non-gardeners	Subjective symptoms, regular visits to the doctor or due to illness or injury, health problems that affect daily life, subjective well-being, reasons for feeling alive, psychological distress and BMI	—	There was a significant relationship between gardening and exercise habits, physical activity, eating vegetables, and relationship with neighbors, no significant relationship with gardening frequency, and a significant relationship with duration.
Shimada et al. (2019)	Obu (Japan)	Case-control study	743 elderly people living in the community	54.29	71.1, SD=±4.5	Gardeners and Non-gardeners to field work or horticultural work	ADL, measurement of cognitive functions and incident AD, GDS	4 years	Working in the field or gardening can help people with mild cognitive impairment recover
van den Berg et al. (2010)	Netherlands	Cohort Studies	121 gardeners with allocated gardens and 63 respondents without gardens in 12 sites in the Netherlands	50.54	61.5, SD=±11.8	Allotment gardeners and their neighbors without an allotment	Self-reported indicators of health, indicators of well-being, and one self-assessed indicator of summer physical activity level reported	—	Allotment gardeners aged 62 and older scored significantly or slightly higher than their neighbors in the same age group on all indicators of health and well-being, with younger allotment gardeners not differing from their younger neighbors.
Soga et al. (2017)	Tokyo (Japan)	Cohort Studies	332 elderly people from questionnaire survey	53.31	61.46, SD=±12.97	Allotment gardeners and non-gardener	Perceived general health, subjective health complaints, BMI, mental health and social cohesion	—	Allotment gardeners, compared to non-gardeners, reported better perceived general health, subjective health complaints, mental health and social cohesion. BMI did not differ between gardeners and non-gardeners.

MMSE: mini-mental state examination; BMI: body mass index; BMD: bone mineral density; ADL: Activities of daily living; GDS: geriatric depression scale