This study explores the effect of green care mental health promotion on the mental health and well-being of adults with a mixed research design. Thirty-two adults from an office building in the downtown area of Taichung City were recruited as research subjects. The researcher applied 12-hour promotion of green care mental health to the subjects, using the Adult Mental Health Scale (AMHS) and Chinese Happiness Inventory (CHI) as research tools to carry out a pretest, posttest, and follow-up test four weeks after the completion of the program. Paired sample t-tests were carried out for the pretest, posttest, and follow-up test scores to verify the research hypotheses. Moreover, the feedback from a questionnaire on the program and their discussions on the program’s web group were also collected and analyzed to understand the effects of green care mental health promotion from a qualitative perspective. The following conclusions can be drawn from the quantitative study: (1) The green care mental health promotion had an immediate and significant positive effect on the mental health and well-being of adults; and (2) it also had a significant positive follow-up effect on the mental health and well-being of adults. The qualitative analysis revealed that the green care mental health promotion had influenced the subjects in three aspects: mental change, change in social interaction, and environmental change. Finally, we provide suggestions based on the findings as a reference for future research and for mental health promotion practitioners.
