Timing for green prescription: comparing the immediate and cumulative effects of different duration horticultural therapy programs on college students' mental health

BackgroundAlthough the mental health benefits of horticultural therapy (HT) are well-established, the influence of intervention duration and the temporal dynamics of effects remain insufficiently explored, lacking evidence for optimal protocol design.MethodsThis study employed a comparative experimental design with a short-duration HT program (4 sessions, n = 12) and a long-duration program (8 sessions, n=14), both conducted weekly. Immediate effects (mood states, affects, facial expressions, sa