Background and objective: This study analyzed the effect size of each element to secure the expertise of horticultural therapy programs for older adults with dementia.Methods: This study conducted a meta-analysis to analyze the effectiveness of horticultural therapy programs for older adults with dementia using 'horticulture' as a search term. To this end, 29 articles were selected and analyzed from a total of 147 articles published between 2003 and 2022.Results: First, the overall effect size of horticultural therapy for older adults with dementia was .522, which is statistically significant. This is considered a medium effect size according to Cohen's (1988) criteria for effect size. Second, the group size, a variable related to the number of subjects, showed the largest effect size when the group had 21–30 participants, and the number of sessions per week showed the largest effect size when the number of sessions was once a week, followed by twice a week, and so on. The effect size was largest when the total number of sessions was 21 or more, and when each session was conducted for 90-120 minutes.Conclusion: This study examined previous studies related to horticultural therapy programs for older adults with dementia through a meta-analysis and presented the results of a systematic effect size analysis. The significance of this study is that it summarized the factors that have a large effect and quantified the effect sizes so that it can be used in various horticultural therapy programs for older adults with dementia.
