Table 2.

Summary information of included studies.

Study	Author(s), Year, Country	Aims	Design	Participants	Intervention or Activity and Intensity	Outcomes	Methods of Data Collection	Main Findings
[47]	Hall et al., (2016) Canada	To examine if and how to increase engagement in horticultural activities through an improved garden design and person-centered recreational programming, compared with more traditional day program activities.	Mixed methods approach. Descriptive analysis and validated observational tool.	A total of 14 participants in early-to-moderate stages of dementia, i.e., diagnosis or suspected diagnosis of dementia, MMSE 16–26, and prior interest in gardening. M = 84 years; 28.6% female.	A structured horticultural therapy program at adult daycare program, 2 times per week for 10 weeks. Activities included herb garden tour, educational presentations, pet therapy or music therapy in the garden, shelling peas, planting seeds, watering plants, cleaning up the garden, etc.	Well-being and engagement. Lasting impacts of engagement in horticultural therapy program.	‘Dementia care mapping’ tool [52], assessed based on observations of participants every 5 min during the program. Questionnaire on lasting impact of the intervention completed by the care partners at the end of 10-week program.	For 77.42% of the time, participants had high well-being and engagement with the horticultural therapy. Participants talked more about their experiences in the garden club, expressed happy and enthusiastic emotion, and viewed their gardening work as their personal accomplishment. Four themes identified from qualitative data: Combining structured and unstructured activities. Importance of teamwork. Garden reminiscence. Positive risk taking.
[48]	Hendriks et al., (2016) Netherlands	To develop an approach and decisional tool for personalized nature activities for PLWD.	Mixed methods. Phases 1 and 2: qualitative descriptive design. Phase 3: qualitative descriptive pilot one-group design; thematic and descriptive statistical analysis.	A total of 34 participants across study 3 phases.	Individual and personalized nature activity, e.g., nature walk or a gardening activity, e.g., sowing, watering, fertilizing, harvesting, and cooking with home-grown vegetables. Pilot study executed in Spring 2015; duration of activity engagement recommended as 45–60 min.	Phase 1: preferred or important aspects or activities in nature or outdoor spaces for PLWD. Phase 2: n/a, tool development. Phase 3: (a) behaviors and mood dysregulation and (b) feasibility of personalized nature activities.	Phases 1 and 2: focus group. Phase 3: semi-structured interviews. Observed Emotion Rating Scale [51], Interact instrument (Dorset HealthCare NHS Trust).	Eight themes emerged when being in nature: pleasure; relaxation; feeling fit; enjoying the beauty of nature; feeling free; the social aspect of nature; feeling useful; memories. Preferred activities: walking, cycling, swimming, exercising, sitting outdoors, watching and talking about nature, activities involving animals, flowers or plants, watching films about nature or handcraft with flowers. The decision tools for designing person-centered activities are considered highly to reasonably feasible.
[42]	Hewitt et al., (2013) U.K.	Explore changes in well-being resulting from participation in a structured group gardening program for people with young-onset dementia.	Mixed methods qualitative and quantitative; pretest and posttest.	A total of 12 people with young-onset dementia. Inclusion: confirmed diagnosis of dementia, being physically active and interested in gardening, having a caregiver available, access to transport to attend the program.	Structured group gardening program, 2 h weekly for 46 sessions, across one year. Participants helped plan session activities, which included digging and planting with spring flowering bulbs, sweeping leaves, etc.	Cognitive level, activity participation, daily living activities, well-being.	MMSE [43] completed at baseline and again at study mid- and end-points; Bradford Wellbeing Profile [52] by staff observations; semi-structured interviews with care partners’ pretest and posttest.	Results of MMSE and the Well-being Profile showed increased well-being for participants, despite cognitive functioning continuing to decline over the one-year period. Caregivers reported that participants displayed a renewed sense of purpose, independence, and self-esteem.
[49]	Jarrott et al., (2002) USA	To compare horticultural activity program to usual activities such as games and crafts.	Quasi-experimental design.	Nine community-dwelling PLWD attending an adult day service.	Horticultural therapy program activities, three times per week across 10 weeks; sessions were 30–45 min. Activities were mostly outside, planting, tending to plants and seedlings.	Activity engagement and affect.	Observational, coding for activity and affect. Affect scale adapted from the Dementia Care Mapping tool [52].	Participants significantly more engaged during the horticultural activity sessions compared with usual activities. Affect indicated ‘moderate well-being’, although not statistically different between activity conditions.
[50]	Lassell et al., (2021) USA	To explore quality of life indicators after engagement in adaptive gardening compared with adaptive horse riding for PLWD.	Descriptive case study design.	Eight participants in early-to-moderate stages of dementia; 4 persons self-selected into the community-based adaptive gardening condition, aged 60–98 years (M = 82).	Weekly, one hour-long community-based gardening for eight weeks, compared with an adaptive (horse) riding program. Activities included planting, harvesting, weeding, exploring the garden.	Quality of life indicators: participation and apparent affect (e.g., anxiety, fear pleasure, interest, gaze).	Modified Activity-in-Context-in-Time, observational tool [53] used to code total of 31 h of videotaped data	Both activities supported ‘positive’ and ‘neutral’ quality of life indicators. Riding provided more opportunities for complex activities compared with gardening (U = 15, p = 0.057), however gardening provided a range of adaptations from more relaxed (e.g., reminiscing, watering) to more active participation (weeding).
[57]	Makizako et al., (2019) Japan	To compare the efficacy of physical exercise, horticulture activities, and control condition.	Single blind RCT	A total of 89 participants with depressive symptoms and mild-memory decline, across 3 conditions: horticulture activities, exercise, control.	Weekly, 60–90 min horticulture-based activity program for 20 weeks. Cultivating, growing, harvesting, group gardening, e.g., planting flowers in public gardens. Exercise included dual-task physical and cognitive, e.g., simple calculation tasks while performing stepping exercises. Control group, education classes involved two 90-min classes, topics, e.g., traffic safety, disaster prevention.	Primary outcome(s) measures, depressive symptoms (Geriatric Depression Scale, GDS-15) [45], and memory performance (Wechsler Memory Scale-Revised) [46].	Three groups compared at baseline, 6 months post-intervention, and 12 months follow-up. Physical performance, social network (Lubben Social Network Scale (LSNS-6) [58], life space, daily physical activity levels (triaxial accelerometer).	GDS-15 scores showed no significant improvements across all groups. Exercise group only obtained higher immediate and delayed recall logical memory scores. Horticulture activity did not improve memory function. Horticulture and control groups showed no differences.
[55]	Noone and Jenkins (2018) UK, Glasgow, Scotland	Exploration of the subjective experience of community-based gardening focused on first person experiences (participants with dementia) and caregivers’ views.	Qualitative design, action research approach.	Six participants with diagnosis of any type of dementia (disease stage not specified) recruited from a day center and three program staff.	Community gardening sessions held once per week for six weeks. Activities included planting seeds and seedlings, making bird feeders.	Qualitative thematic analysis of participants’ experiences attending community-based gardening program and views of day center staff.	Semi-structed group interviews with participants and individual interviews with three staff following each of the gardening sessions; researcher reflections.	Gardening is an articulation of identity and selfhood and an expression of agency. It also helps develop new social bonds based on shared interests. Three themes to emerge from interviews were: (i) identity, (ii) agency, (iii) community.
[54]	Smith-Carrier et al., (2019) Canada	To explore emotional and sensory experiences of therapeutic gardening for persons with dementia.	Qualitative design.	Six persons with early-stage dementia attending an adult day center.	Therapeutic group gardening program, six waves across five months of spring and fall activities, e.g., planting, harvesting, pruning, clean-up, etc.	Interpretive analysis of participants’ reflections on sensory and emotional experiences in the gardening process.	Six repeated interviews with participants with dementia.	Themes derived from analysis of interviews provided support for the value of gardening for activating the senses, meaningful occupation, socialization, and mental and physical well-being.