Table 4 Studies addressing psychosocial outcomes included in this review

Brown et al. 2020 [25]

USA, Montana, Native American community

RCT

(1) Group-based Community gardening program

(2) control (no gardening)

Native Americans with prediabetes or diabetes

N = 20

Age (y):

15/20 were 45–64 years, 5/25 25–44 years

Male n(%): 4/20 (25%)

CON n = 12

INT n = 8

Determine feasibility of a group gardening program and potential for collecting health outcomes

Convenience sample of participant expressing an interest in the gardening study at a diabetes clinic

Raised beds for gardening chosen for proximity to college and health centre. Plus 10 × 90-min structured sessions with hands-on gardening and food preparation activities

Outcomes measured at 7 months after baseline

Outcomes were reported as medians and ranges. Change from baseline was compared between the groups using Wilcoxon rank sum tests. No adjustments

Sample numbers reported for each outcome as there was missing information for some outcomes

Quality of life (QOL), CES

Depression Scale

Tension-anxiety, depression-dejection, anger-hostility, vigour-activity, fatigue-inertia, and confusion-bewilderment (from Profile of Mood States Inventory—POMS)

QOL – psychological

INT (n = 7) 0 [-3.3, 2.0]

CON (n = 11) 0.2 [-4.0, 4.5]

P = 0.772

QOL – social

INT (n = 7) 0 [0, 2.0]

CON (n = 11) 0.2 [-6.7, 4.0]

P = 0.430

QOL – environment

INT (n = 7) -1.0 [-1.5, 0.5]

CON (n = 11) 0 [-0.5, 4.0]

P = 0.013

QOL – physical

INT (n = 7) -0.6 [-1.7, 0.6]

CON (n = 11) -0.6 [-5.1, 2.9]

P = 0.707

POMS – total mood disturbance

INT (n = 8) -2.0 [-16, 18]

CON (n = 9) 9 [(-1.0, 30]

P = 0.049

POMS – tension anxiety

INT (n = 8) − 0.5 (− 4.0 to 6.0)

CON (n = 10) 1.0 (− 2.0 to 12.)

P = 0.062

POMS – depression-dejection

INT (n = 8) − 0.5 (− 4.0 to 6.0)

CON (n = 10) 3.5 (− 2.0 to 19)

P = 0.105

POMS – anger-hostility

INT (n = 8) 0 (− 8.0 to 10)

CON (n = 9) 6.0 (− 6.0 to 20)

P = 0.180

POMS – vigor-activity

INT (n = 8) − 3.0 (− 13 to 13)

CON (n = 9) 0 (− 7.0 to 7.0)

P = 0.382

POMS – fatigue-inertia

INT (n = 8) − 2.5 (− 16 to 7.0)

CON (n = 10) 2.0 (− 10 to 21)

P = 0.246

POMS – confusion-bewilderment

INT (n = 8) 0 (− 4.0 to 6.0)

CON (n = 9) 2.0 (0 to 17)

P = 0.119

Gerber et al. 2017 [56]

USA

Cross-sectional survey

Bhutanese community leaders recruited participants & collected data

Bhutanese refugees in the USA who self-select as community gardeners (n = 22) or non-gardeners (n = 28)

Characteristics

Female: 62%

Age (mean ± SD): 45 ± 15 yrs

To explore differences in indicators of distress and social support among Bhutanese refugees that participate in community gardens compared with those who do not

Bhutanese community events, word-of-mouth

Waiting list for plots. Families typically garden on one or two plots

Descriptive statistics only. No comparisons, & not adjusted for anything

Symptoms of post-traumatic stress disease, anxiety & depression using the Refugee Health Screener (15-items, score > 12 refer to mental health service)

Patient Health Questionnaire (15-items, 3-point scale; cut-points 5, 10 & 15 indicate low, medium and high somatic symptoms)

Perceived social support (Medical Outcomes Study Social Support Survey; 19-item, 5-point scale)

On average, more Gardeners lived in a house, and had lower medical bills, compared with non-gardeners

Refugee Health Screener referrals

(mean ± SD)

Gardeners: 11.6 ± 9.2

Non-gardeners: 11.0 ± 9.9

Comparisons “not statistically different”

Scores > 5 on Patient Health Questionnaire

Gardeners: 14/22 (64%)

Non-gardeners: 13/28 (46%)

Gardeners experienced more somatic symptoms

Standardized effect size (d = 0.36 95% CI -0.21, 0.91)

Social support

(mean ± SD)

Gardeners: 61.3 ± 13.2

Non-gardeners: 52.5 ± 12.1

Gardeners reported more social support Standardized effect size (d = 0.70 95% CI 0.12, 1.27)

Grier et al. 2015 [57]

USA; Dan River, Virginia

Pre-/post

n = 43

Characteristics

Ethnicity: 97.7% African American

Age (mean) 8.7y

Male: 46.5%

Weight status: 34.1% overweight

18.2% obese

Inclusion criteria

Age: 5–17 y

Child AND parent reside in housing authority full-time

To report on feasibility (demand, acceptability, implementation and limited-effectiveness) of a CG and nutrition education program

Two public housing authority sites – active members of the Dan River Partnership for a Healthy Community

Adult site leaders knew families and youth; distributed recruitment material

Junior Master Gardener curriculum with nutrition focused lessons (informed by SCT). Weekly gardening sessions or gardening + nutrition education with site leaders

Interviewer administered survey

Repeated measures ANOVA (ITT and complete case; ITT presented); effect sizes calculated

Psychosocial factors related to F&V consumption (not actual consumption) and nutrition knowledge

Increased self-efficacy for asking for F&V (ES: 0.39; p = 0.013)

No change in willingness to try F&V (ES = 0.10; p = 0.310), self-efficacy for eating F&V (ES = 0.21; p = 0.119) or nutrition knowledge (ES = 0.10; p = 0.583)

Hawkins et al. 2011 [49]

UK, Wales, Cardiff

Cross-sectional study

(1) Indoor exercise group

(2) Walkers

(3) Allotment gardeners

(4) Home gardeners

Characteristics

(1) n = 23

Age (y): 72.9 ± 6.9

Male: 3 (13%)

(2) n = 25

Age (y): 62.4 ± 6.8

Male: 8 (32%)

(3) n = 25

Age (y): 65.7 ± 9.1

Male: 17 (68%)

(4) n = 21

Age (y): 69.5 ± 7.7

Male: 2 (10%)

Inclusion criteria

 ≥ 50 y attending various local activity groups

Measure health status and perceived stress of allotment gardeners compared to other activity groups (indoor exercisers, walkers, home gardeners)

Recruited via leaflets, posters and visits to groups from researcher

Response rate 87.8%

Compared leisure activity groups to members of allotment gardening group

No intervention

Perceived stress: Cohen & Williamson 1988

Health-related Quality of Life, (Mental health component) using the SF-36v2

Social provisions

Stress level btw groups adjusted for area-level SEP

Perceived stress

Significantly lower perceived stress among allotment gardeners than other activity groups

Perceived stress (mean ± SD)

(1) 15.8 ± 6.1

(2) 13.6 ± 5.4

(3) 9.8 ± 5.8

(4) 12.0 ± 4.8

QOL Mental health (median, IQR)

(1) 50 (46.6–54.4)

(2) 56.1 (51.7–58.4)

(3) 55.3 (50.1–58.6)

(4) 55.8 (50.7–58.8)

Hartwig and Mason 2016 [33]

USA, MN, Twin Cities

Cross-sectional surveys

n = 97

Characteristics

Female: 65%

English: 18% good/fluent

Age (mean): 39y

(16–80 y)

Ethnicity: 67% Karen (Burmese)

To evaluate church CGs serving refugee and immigrant populations, reporting primary health and social benefits

All gardeners at 8 gardens invited (Response rate = 44–45%)

Gardens purposively sampled based on:

- 2 yrs participation

- # gardeners

- primary language of gardeners

8 church gardens serving refugees and immigrants

Measured early and late season harvest (Jul-Sept)

Descriptive stats used: change in mean/% early and late season

No adjustments

Depression

Gardening alone/with others (social interaction)

Change in depression risk not reported (12% reached cut-off for additional screening)

Frequency of social interactions declined from early to late season harvest

Heilmayr and Friedman, 2020 [34]

USA, CA

RCT with 5 INT groups:

(1) Community gardening

(2) moderate indoor exercise

(3) Exposure to nature

(4) Social club (watching films)

(5) Indoor container gardening

University students

Baseline data reported in combination (not by group allocation)

Age (y): 20.6 ± 3.3

Male: 31.2%

(1) n = 21

(2) n = 21

(3) n = 23

(4) n = 22

(5) n = 23

To compare community gardening with four theoretically driven comparison groups to understand possible causal mechanisms around how community gardens have improved outcomes

Convenience sample recruited via flyers, emails and the Psychology Subject Pool

4 week INT; assigned an activity for 2–3 h/wk

Data were analyzed by ANOVA with pre-/post-test values to assess how groups changed from baseline and a group by time interaction

Emotional wellbeing (Comprised of: Perceived stress, Happiness, Self-efficacy, Positive and Negative Affect)

Social relationships (Comprised of: Companionship, Social integration)

Emotional wellbeing (post-test only; mean ± SD)

(1) 65.4 ± 14.8

(2) 66.6 ± 15.5

(3) 66.1 ± 13.3

(4) 63.6 ± 15.5

(5) 67.1 ± 14.4

Social relationships (post-test only; mean ± SD)

(1) 62.3 ± 10.8

(2) 63.5 ± 11.9

(3) 59.3 ± 14.1

(4) 59.3 ± 16.6

(5) 60.7 ± 11.4

Hopkins and Holben 2018 [35]

USA, OH, rural Appalachia (Athens)

Cross-sectional study

-n = 50

Inclusion criteria:

CG plot in Athens

Characteristics

Ethnicity: 81.6% white

Female: 67.4%

Education:46.9% college educated

To examine relationships among food security, produce intake and behaviors, health and social capital among community gardeners

All community gardeners (n = 120) in Athens

No INT

Individuals with CG plots

Survey distributed via email (Response rate = 42%)

Descriptive stats reported, no adjustment

Social capital

(made new friends)

Social cohesion

74% have made new friends due to CG

No association of food security with social capital

Koay et al. 2020 [58]

Singapore

Cross- sectional survey

(1) Community gardener

N = 45

Male n (%): 25(56%)

Age (mean ± SD): 60.2y (± 13.3)

Ethnicity: 40 (89%) Chinese

Education: 18(40%) Tertiary

(2) Home gardener

N = 38

Male n(%) 6(84%)

Age (mean ± SD): 43.8 ± 13.0

Ethnicity: Chinese 35(92%)

Education: Tertiary 33(87%)

(3) Non-gardening control

N = 28

Male n (%) 12(43%)

Age (mean ± SD): 55.5 ± 11.6

Ethnicity: Chinese 23(82%)

Education: Tertiary 13(46%)

Study relationship between community gardening and mental health benefits

Snowball recruitment from gardens and outdoor activity groups

Community in Bloom program of government supported

Multivariate ANCOVA with adjustment for age and connection to nature

Perceived stress scale (10-item, 5-point scale)

Personal Wellbeing Index (7-item, 11 point scale)

Brief resilience scale (6-item, 5-point scale)

Perceived stress scale (mean ± SD)

(1) 11.4 ± 6.4

(2) 15.5 ± 6.1

(3) 7.0 ± 0.8

Personal wellbeing index (mean ± SD)

(1) 8.2 ± 1.1

(2) 7.0 ± 1.2

(3) 7.0 ± 0.8

Brief resilience scale (mean ± SD)

(1) 3.7 ± 0.7

(2) 3.5 ± 0.6

(3) 3.0 ± 0.8

Litt et al. 2015 [38]

USA; Denver, Colorado

Cross-sectional survey

n = 469

Characteristics

Age (mean): 46.1y (± 15.9)

Female: 67.4%

Education: 57.4% college educated

Identified as gardeners: 59.3%

Inclusion criteria

English or Spanish speaking, ≥ 18yrs

To examine the direct and indirect pathways by which gardening influence self-rated health

Area-based sample of general population n = 1154 randomly drawn from 40 block groups

13 gardens identified; List-based census of community gardeners n = 300

No intervention

Individuals participating in CGs compared with non-gardeners

Surveys interviewer administered

Path analysis controlling for age, education, years in neighborhood, % college education in neighborhood, observed incivilities

Social involvement

Collective efficacy

Neighborhood attachment

Path model results:

Data fit model adequately, accounting for 22% variance in self-rated health and 4% in F&V intake

Gardening predicted social involvement (β = 0.36; p < 0.001)

Social involvement (β = 0.11, p < 0.05) and aesthetics (β = 0.46, p < 0.001) predicted Collective efficacy

Collective efficacy predicted neighborhood attachment (β = 0.29, p < 0.001)

Machida 2019 [39]

Japan

Cross-sectional survey

Web-based survey limited to age 60–69 y, professional farmers excluded

(1) Community gardeners n = 129

Male n (%): 87(67%)

Age (y): 64.1 ± 2.6

(2) Home gardeners (HG) n = 371

Male n(%):280(76%

Age (mean ± SD): 63.9y ± 2.7

(3) Non-gardeners n = 500

Male n(%): 327 (65%)

Age (mean ± SD): 63.3y ± 2.5

To study the relationship between community or home gardening and health status or a healthy lifestyle

The survey was conducted by a marketing company with 4.2 million people registered across all 47 prefectures in Japan

NA

Odds Ratios adjusted for sex, age, family structure and employment status (not described)

Happiness (single item, 11-point scale) dichotomized to ≤ 6 vs ≥ 7

Psychological distress using 4 items of the K6 (4-point scale) dichotomized at ≤ 8 vs ≥ 9

Happiness

(1) CG: 1.60 (1.18, 2.16)

(2) HG: 0.89 (0.59, 1.34)

Distress

(1) CG: 0.85 (0.57, 1.27)

(2) HG: 0.72 (0.38, 1.36)

Mourao et al. 2019 [54]

Portugal

Cross-sectional survey

Invitation from the Urban Allotment Garden office, sent to 30 gardeners per session. Six sessions performed, resulting in 65 validated responses

Lived in urban areas of the council, 90.8%

Characteristics

Male: 56.9%

Age:

26–45 yrs: 36.9%

46–65 yrs: 47.7%

 > 65 yrs: 15.4%

To evaluate the happiness and well-being of the Portugal population, based on the urban organic allotment gardens

Self-administered questionnaires

Permanent resident, garden a family plot

Pearson correlation. No adjustment

Personal wellbeing scale

Subjective happiness scale

Gardening frequency:

Once a week: 10.5%

Few days a week: 47.7%

Daily: 41.5%

Degree of life satisfaction (personal well-being index): Mean 74.5% (0–100%)

Greater frequency to gardens was associated with higher perspective of subjective happiness and compared to their peers

Soga et al. 2017 [50]

Japan, Tokyo, Nerima district in central Tokyo

Cross-sectional survey

Gardeners (n = 165) vs non-gardeners (n = 167)

Characteristics

Gardeners:

Male: 68.1%

Age (mean ± SD): 62 ± 17y

Non-gardeners:

Male: 42%

Age (mean ± SD):

61 ± 16y

To quantify effects of allotment gardening on physical, psychological and social health

Gardeners located by face-to-face recruitment at allotment gardens (90% response rate). Non-gardeners recruited via a letter sent to 1000 Nerima households (20% response rate)

No INT

Adjusted for sex, age, household income, employment, smoking, drinking, vegetable intake and PA (days per week of > 30 min/day of moderate activity)

Mental health using 12-item General Health questionnaire (scores 0–12)

Mental health

Compared with non-gardeners, mean mental health scores for gardeners (± SE) was -0.91 (0.42) higher (P < 0.05), indicating improvements in mental health

Swami 2020

[59]

UK, London

Cross-sectional survey

English-speaking adults. One participant per allotment

(1) allotment gardeners (n = 84)

(2) non-gardeners (n = 81)

Full sample

Male (%): 40%

Age (mean ± SD): 44.7y ± 18.2

To examine the effect of allotment gardening on state body image

Gardeners recruited from 12 allotment sites via direct approach. Non-gardeners recruited from supermarkets closest to the allotment sites. They could no “do anything in the garden”

Not described

Non-gardeners ‘matched’ to gardeners but no description of matching process or characteristic. Analysis by unpaired t-test with no adjustments (including no adjustment of matching criteria)

Bonferroni correction of p values

State body image using a 10 cm visual analogue scale

Body Appreciation Scale-2 (10-items, 5-point scale)

Functionality Appreciation Scale (7-item, 5-point scale)

Authentic Pride subscale of the Body and Appearance Self-Conscious Emotions Scale (6-items, 5-point scale)

Body appreciation (mean ± SD)

(1) 3.5 ± 0.8

(2) 3.1 ± 0.8

Functionality appreciation (mean ± SD)

(1) 3.5 ± 0.7

(2)3.2 ± 0.8

Body pride (mean ± SD)

(1) 3.1 ± 0.9

(2) 2.6 ± 0.9

Tharrey et al. 2020 [46]

France, Montpellier

Longitudinal cohort study

Data collected at baseline and 1 year later

Characteristics

(1) Community gardeners (n = 66)

Male n(%): 16(24.2)

Age (y): 44.0 ± 14.0

(2) Non-gardeners (n = 66)

Male n (%): 16(24.2)

Age (y): 44.9 ± 13.7

Inclusion criteria

Starting gardening in a CG; residents of Montpelier; ability to read French

To assess the impact or urban community garden participation the adoption of sustainable lifestyles

Gardeners recruited when new to the gardening community

Non-gardeners recruited via volunteers for a population-based survey on food supply behaviors

Community gardens plots used collectively or individually

Analyzed with mixed-effects models with group by time interaction

Adjustments for education, BMI, meals consumed outside the home, social desirability where appropriate

Warwick-Edinburgh Mental Wellbeing Scale (WEMWBS; 14-item, 5-point scale)

Loneliness scale v3 (20-items 4-point scale)

Wellbeing at 1 year (mean ± SD)

(1) 51.5 ± 6.9

(2) 51.5 ± 5.7

Loneliness at 1 year (mean ± SD)

(1) 40.1 ± 10.9

(2) 40.5 ± 9.5

van den Berg et al. 2010 [51]

The Netherlands, “large cities”

Cross-sectional survey

Gardeners (n = 121) from 12 allotment gardens

Non-gardener (n = 63)

Characteristics

Gardeners:

Male: 53%

Age (mean ± SD): 62 ± 12 y

Non-gardeners:

Male: 41%

Age (mean ± SD):

56 ± 14 y

To directly compare the health, wellbeing and physical activity of allotment gardeners to that of controls without an allotment garden

Gardeners sent invitations to their home addresses

Non-gardeners were responders living next to the home address of allotment gardeners

Ranged from residential parks, day-recreational parks and food production parks

Adjusted for age, sex, education, income, access to a garden at home, PA in winter and stressful life events, and included an age by gardening interaction term. Results separated by age. For all outcomes

Stress in past month (2-items,

6-point scale), Life Satisfaction Index (8-item, 3-point response)

Loneliness (2-items, 0–1 responses)

Social contacts (2-items, scores range 1–12)

All mean_adjusted ± SE

Stress

 < 62 yrs

Gardeners 3.2 ± 0.1

Non-gardeners 2.9 ± 0.2

 ≥ 62 yrs

Gardeners 2.1 ± 0.1

Non-gardeners 2.5 ± 0.2

Life satisfaction

 < 62 yrs

Gardeners 2.2 ± 0.1

Non-gardeners 2.2 ± 0.1

 ≥ 62 yrs

Gardeners 2.3 ± 0.1

Non-gardeners 2.0 ± 0.1

Loneliness

 < 62 yrs

Gardeners 0.7 ± 0.1

Non-gardeners 0.6 ± 0.1

 ≥ 62 yrs

Gardeners 0.3 ± 0.1

Non-gardeners 0.8 ± 0.2

Social contacts

 < 62 yrs

Gardeners 6.1 ± 0.4

Non-gardeners 7.0 ± 0.5

 ≥ 62 yrs

Gardeners 8.1 ± 0.4

Non-gardeners 6.2 ± 0.7

Young et al. 2020 [60]

Switzerland, Zurich

Cross-sectional survey

Materials provided in 4 languages used locally. Limited to one person per allotment

(1) Allotment gardeners (n = 108)

Male (%): 52%

Age (y): 59 (SD NR)

(2) Domestic gardeners (n = 193)

Male (%): 33%

Age (y): 54 (SD NR)

To identify whether gardening is a source of stress (i.e. stress as a result of the garden)

Allotment gardeners drawn in a two-stage probabilistic sampling strategy (response rate 48%.) Domestic gardeners drawn from a random sample of individuals living in Zurich (response rate 27%)

Allotments typically 100–200 m2, with rules to prohibit invasive species and construction on site. Domestic gardens are available to householders who can afford to buy/rent a residence with a garden (~ 10% of population)

Independent t-test

Structural equation model (SEM) with robust standard errors, full information maximum-likelihood for missing data and adjustment for age, gender, employment, job type and biodiversity preference

Single question “I often feel under pressure when I think of the tasks that need doing in my garden” (5-point response)

Garden-related stress (mean ± SD)

(1) 2.2 ± 1.2

(2) 2.5 ± 1.1

Allotment gardeners reported lower stress than domestic gardeners (β = -0.167, p = 0.013) when controlling for socioeconomic variables in SEM