| Active people–plant interactions |
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| 1. | Bassi et al. (2018) | Italy | 11 residents of a nursing home (both occupational activities and HT | Crossover study with a baseline measureTwo cycles, 6 weeks × 1 × 60 min each | Psychological tests | Increase of cognitive and motivational variables, during both activities, and improved self-satisfaction in comparison with occupational therapy treatment. Horticulture was recognised as more challenging than occupational therapy treatment |
| 2. | Chen and Janke (2012) | USA | 3237 seniors (clients gardeners, control nongardeners) | At least 1 h per week | Physiological and functional testsSelf-reported measure of health status | Significantly better balance and improved gait were reported by gardeners, they also had fewer functional limitations and chronic conditions than nongardenersFalls in the past 2 years were rarer in the gardeners group than in the nongardeners group |
| 3. | Chen and Ji (2015) | Taiwan | 10 residents of a nursing home (clients with indoor HT program) | Preliminary study, combined quantitative and qualitative design10 weeks × 1 × 90 min | Background data sheetPsychological tests | HT program resulted in encouragement of social connections and companionship, hope, anticipation and a sense of achievement. Levels of depression and loneliness significantly increased |
| 4. | Chu et al. (2021) | Taiwan | 88 residents of nursing homes (clients horticultural activities, control leisure activities) | Quasi-experimental, nonequivalent pretest-posttest control group design8 weeks × 1 × 120 min each | Sociodemographic questionerPsychological testsPhysiological and functional tests | ‘Attitudes toward ageing’ and ‘sense of hope’ increased after the intervention. The experimental group significantly improved the time required to complete the cup stacking test |
| 5. | Freeman et al. (2019) | New Zealand | 72 seniors | In-depth, qualitative interviewsNot stated | Individual interviews | Older adults highly value the direct engagement with nature, even when limited by health |
| 6. | Han (2017) | Korea | 40 female members of I Church (clients with HT program, control no intervention) | Quasi-experimental, nonequivalent pretest-posttest control group design8 weeks × 1 × 90–120 min | Psychological testsPhysiological and functional tests | Significant pre-post improvement in all sub-factors of self-respect and in all sub-factors of personality and talent in the experimental group |
| 7. | Kim et al. (2021) | South Korea | 58 seniors (both horticultural and non-horticultural activities) | Cross-over experimental design1 day × 8 × 2 min | Psychological testsPhysiological and functional tests | The results of the POMS showed that during horticultural activities the total mood disorder score was lowered. Brain activity of older adults may be increased by activities such as washing leaves, transplanting, and reading news and that has a positive effect on their cognitive function |
| 8. | Lai et al. (2018) | China | 111 residents of nursing homes (clients with HT program, control no intervention) | RCT8 weeks × 1 × 60 min | Psychological testsPhysiological and functional tests | Significant increase in the subjective happiness after the HT program |
| 9. | Lee (2019) | Korea | 58 residents of a nursing home (clients with HT program, control no intervention) | Quasi-experimental, pretest-posttest control group design10 weeks × 1 × 50 min | Physiological and functional tests | Significant pre-post decrease in the positive domain in the control group and non-significant in the experimental groupSignificant pre-post decrease in mean score of neuroticism and physiological domain in the experimental group |
| 10. | Lo et al. (2019) | China | 22 residents of nursing homes (clients with HT program) | RCT with a qualitative descriptive approach8 weeks × 1 × 60 min | Individual semi-structured interviews | Clients of nursing homes saw HT as an enjoyable activity and a good pastime, which made them happier.Horticultural activities resulted in socialisation among the residents |
| 11. | Masuya et al. (2014) | Japan | 18 residents of a nursing home (clients with HT program, control no intervention) | Quasi-experimental, nonequivalent pretest-posttest control group design6 weeks × 1 × 30–40 min | Psychological testsPhysiological and functional tests | Significant improvement in satisfaction with life and a significant decrease in GDS score after the interventionNo significant pre-post change in vitality Index, Activities of Daily Living Scale, and MMSE scores in both groups |
| 12. | Ng et al. (2018) | Singapore | 59 seniors recruited from the neighbourhood (clients with HT program, control no intervention) | RCTStage 13 months × 1 × 60 min Stage 23 months × once a month × 60 min | Physiological and functional testsPsychological tests | A significant reduction in plasma IL-6 level in the HT intervention groupSocial connectedness significantly improved in the HT groupSignificant reductions in plasma CXCL12 (SDF-1), CXCL5 (RANTES) and BDNF in the control group |
| 13. | Ng et al. (2021) | Singapore | 59 seniors (clients HT intervention, control waitlist) | Secondary analysis of an RCTStage 13 months × 1 × 60 minStage 23 months × once a month × 60 min | Psychological testsPhysiological and functional tests | Social connectedness significantly increased and Log10 IL-6 levels significantly decreased after HT. |
| 14. | Park et al. (2016) | South Korea | 50 seniors recruited from senior community centres (clients with gardening intervention, control no intervention) | Quasi-experimental, nonequivalent pretest-posttest control group design3 months × 2 × 50 min | Physiological and functional testsSociality surveyPsychological tests | Significant pre-post improvement in hand dexterity, aerobic endurance, muscle mass, cognitive ability, and decreased waist circumference in the gardening group. Significant pre-post decrease in agility and muscle mass, and a significant increase in depression in the control group. |
| 15. | Park et al. (2019) | South Korea | 41 seniors recruited from community and welfare centres (clients with gardening intervention) | Quasi-experimental, one group pretest-posttest design1 day × 1 × 20 min | Physiological and functional tests | Significant increase in levels of PDGF and BDNF after the gardening activity |
| 16. | Park et al. (2020) | South Korea | 40 seniors recruited from the senior welfare centre (clients with gardening intervention, control no intervention) | Quasi-experimental, nonequivalent pretest-posttest control group design12 weeks × 2 × 60 min | Physiological and functional testsPsychological tests | Significant pre-post improvements in BDNF levels, hand dexterity, better cognitive ability and improvements in cognitive health in the gardening groupSignificantly higher scores in MMSE of the gardening group after the programNone of the groups showed significant differences in the pre-/post-scores of all SFT items |
| 17. | Perkins (2012) | USA | 31 seniors recruited from independent, community-based, age-restricted residences (clients with HT program, control no intervention) | Quasi-experimental, pretest-posttest control group design6 weeks × 1 × 90 min | Psychological testsGarden Questionnaire developed by the investigator | Significant variance in self-esteem and garden knowledge between the groupsNo significant differences in psychological well-being, garden experience, or social connectedness between the treatment group and the control groupMost helpful parts of classes were learning about herbs and their uses, growing and using herbs, participating in the class (the social aspect) |
| 18. | Robbins and Seibel (2019) | USA | 27 older African Americans | In-depth, qualitative interviewsNot stated | Individual interviews | Gardening lay a part in the well-being of older adults.Plants and gardening practices provided perspectives on the transformations of social dimensions |
| 19. | Scott et al. (2014) | Australia | 331 senior gardeners | A self-administered surveyMedian time per week – 8 h | Gardening benefits questionnaireGardening activity inventoryPsychological tests | Participants felt that gardening was more than a casual leisure activity, they emphasised it as crucial to their psychological and physical wellbeingThey reported that gardening has numerous psychological, physiological and tangible benefits |
| 20. | Scott et al. (2016) | Australia | 331 senior gardeners | A self-administered surveyMedian time per week – 8 h | Gardening benefits questionnaireGardening activity inventoryPsychological tests | Leisure gardening derived numerous benefits for the participants. Gardening was seen as a crucial activity to their well-being and to ageing positively |
| 21. | Scott et al. (2019) | Australia | 331 senior gardeners | A self-administered surveyMedian time per week – 8 h | Gardening benefits questionnaireGardening activity inventoryPsychological tests | Positive ageing self-perceptions were mostly influenced by restoration and physical benefits of gardeningMore physical and social benefits were reported by gardening group members than non-members |
| 22. | Sia et al. (2020) | Singapore | 47 seniors recruited from senior day care centres (clients with HT program) | Experimental, one group pretest-posttest design24 weeks × 1 × 60 min | Psychological testsPhysiological and functional tests | Significant increase in cognitive functions and mean happiness. Reduction in anxiety. Sustained psychological health and sleep patterns |
| 23. | Tse (2010) | China | 53 residents of a nursing home (clients with indoor gardening program, control no intervention) | Quasi-experimental, nonequivalent pretest-posttest control group design8 weeks × not stated | Psychological testsPhysiological and functional tests | Life satisfaction and social network significantly improved and perception of loneliness significantly decreased in the experimental group after the intervention |
| 24. | Tu et al. (2020) | Taiwan | 27 seniors who attended Fooyin University Senior Citizens Learning Camp (clients with HT program) | One group pretest-posttest design2 weeks × 2 × 60 min | Physiological and functional testsPsychological tests | Significantly lower SAA and pulse rate after activities Mood states significantly improved for Rocky Leaf Prints and Herb Tasting and Smelling |
| 25. | Widodo et al. (2019) | Indonesia | 14 senior residents of Batu City (clients with the gardening program, control no intervention) | Quasi-experimental, pretest-posttest control group design6 months × daily × not stated | Physiological and functional tests | Pre-post improvement in anxiety and stress levels in the experimental group (42.9%) and in the control group (28.6%) |
| 26. | Wong et al. (2021) | Singapore | 59 seniors (clients HT intervention, control waitlist) | RCTStage 13 months × 1 × 60 minStage 23 months × once a month × 60 min | Sociodemographic questionerPhysiological and functional tests | Reduction in the levels of biomarkers that indicates the extent of T-cell exhaustion and inflammation in older adults is associated with HT. Pre-post reduction of IL-6 levels |
| 27. | Wu et al. (2020) | Taiwan | 17 seniors recruited from a community care centre for the elderly (clients with HT program) | Quasi-experimental, one group pretest-posttest design12 weeks × 1 × 120 min | Psychological testsSemi-structured interviews | Immediate and significant improvement in overall cognitive function after the HT program.Interviews revealed that: ‘the HT program was meaningful and encouraged the elderly to be engaged in the activities and recall the past, improved enjoyment and learning motivation and ensured new planting experience’ |
| 28. | Yao and Chen (2017) | Taiwan | 85 senior residents of nursing homes (clients with HT program, control no intervention) | Quasi-experimental, pretest-posttest control group design8 weeks × 1 × 60 min | Psychological testsPhysiological and functional tests | Significant pre-post improvement in physical abilities, happiness, meaning of life, and interpersonal intimacy in the experimental group |
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| Passive people–plant interactions |
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| 29. | Dahlkvist et al. (2016) | Sweden | 290 residents of nursing homes (self-motivated garden visits) | Multi-level, cross-sectional, correlational design Not stated | Psychological tests | Positive and significant effect of greenery on self-perceived healthHealth appears to be affected by garden greenery by providing possibilities to experience the outdoor environment as interesting and encouraging and enhancing a sense of being away |
| 30. | Finlay et al. (2015) | Canada | 141 community-dwelling older adults (everyday experiences with green spaces) | In-depth, qualitative interviewsNot stated | Individual interviews | Green and blue spaces have an influence on physical wellbeing (motivation for physical activity), mental wellbeing (sense of improvement, feelings of renewal, restoration, rejuvenation, relaxation and stress reduction) and social wellbeing (social interactions, multi-generation enjoyment) |
| 31. | Gagliardi et al. (2020) | Italy | 19 seniors who joined the environmental volunteering and socialising activities in a city park program (park restoration and social activities) | Quasi-experimental, one group pretest-posttest design1 year × 2 × depends on participants | Physiological and functional testsPsychological testsIndividual interviews | Volunteers increased their weekly engagement in gardening activities and time spent performing voluntary work. They also cared for other people more and had better life satisfaction |
| 32. | Hassan et al. (2019) | China | 50 women residents of a nursing care facility (clients with visual stimulation with a money plant, control visual stimulation without any plant) | Quasi-experimental, pretest-posttest control group design2 days × 2 × 5 min | Physiological and functional testsPsychological tests | Significant pre-post decrease of systolic blood pressure and total state-trait anxiety scores in the experimental groupNo change in diastolic blood pressure between conditions.Variations in both high alpha and high beta brainwaves in the experimental group |
| 33. | Irvine et al. (2020) | UK | 13 seniors recruited from Group Outdoor Health Walk Program (outdoor walks) | Observational pretest–posttest study with convergent mixed methods design12 weeks × depends on the route | Physiological and functional testsPsychological tests Individual interviews | Self-reported physical activity improved during the study. Participants experienced more positive emotions and felt they had more energyClinically relevant changes in experiencing vibrant senses, feeling energised, focused, joyful and calm, as well as sleeping well |
| 34. | Reynolds (2016) | USA | 32 residents of facilities (independent living, assisted living, personal care) (garden use) | A qualitative study of participant observations with behaviour mapping and individual and focus-group interviews, using a grounded theory methodologyDepends on participants | Participant observationsIndividual interviews | High value for nature reported by all participants (essential to their well-being)Nature was valued as an affinity for life, and plants almost as people |
| 35. | Wood and Smyth (2020) | UK | 45 healthy participants recruited from the University of the Third Age (Green exercise) | Pilot study24 h | Physiological and functional testsPsychological tests | Nature exposure and Green Exercise in childhood significantly predicted nature exposure and Green Exercise in adulthoodCN was negatively linked to stress and positive linked to HRV during sleepHigher CN was correlated with less stress reactions and higher rate variability during sleep which both are indicators of health |
