RESUMEN
During the COVID-19 pandemic, the world population faced various mental health challenges, highlighting a need for new community-based psychosocial interventions. This study aimed to investigate the effectiveness and feasibility of Nature-Based Therapy (NBT) for the community experiencing psychological distress during the pandemic. A multi-site trial comparing NBT and control groups was conducted in Korea with 291 participants exhibiting mild to severe depression or anxiety. A total of 192 participated in 30 sessions of therapeutic gardening, while 99 remained in the control group. Psychological distress and well-being were assessed using seven measures of depression, anxiety, daily activity, life satisfaction, mindfulness, stress, and loneliness. The effect sizes (Cohen's d) of NBT compared to the control group were medium to large: depression (0.583), anxiety (0.728), daily activity (1.002), life satisfaction (0.786), mindfulness (0.645), stress (0.903), and loneliness (0.695). Multilevel analysis revealed significant Time × Group interaction effects for all measures. Pearson correlation (r = - 0.28 to 0.71) showed that changes in all variables correlated significantly with each other, with small to large effect sizes. Therapeutic alliance at post-test positively moderated the intervention effects on the outcomes. We concluded that NBT is a promising psychosocial intervention for treating psychological distress for community dwellers.