The objective of this study was to compare physiological and psychological relaxation by assessing heart rate variability (HRV), prefrontal cortex activity, and subjective indexes while subjects performed a task with and without foliage plants. In a crossover experimental design, 24 university students performed a task transferring pots with and without a foliage plant for 3 min. HRV and oxyhemoglobin (oxy-Hb) concentration in the prefrontal cortex were continuously measured. Immediately thereafter, subjective evaluation of emotions was performed using a modified semantic differential (SD) method and a profile of mood state questionnaire (POMS). Results showed that the natural logarithmic (ln) ratio of low frequency/high frequency, as an estimate of sympathetic nerve activity, was significantly lower while performing the task with foliage plants for the average 3 min measurement interval. Oxy-Hb concentration in the left prefrontal cortex showed a tendency to decrease in the 2–3 min interval in the task with foliage plants compared to the task without plants. Moreover, significant psychological relaxation according to POMS score and SD was demonstrated when the task involved foliage plants. In conclusion, the task involving foliage plants led to more physiological and psychological relaxation compared with the task without foliage plants.

This study was conducted to determine the physiological and psychological benefits of foliage plants as visual stimuli. Twenty-three elementary students (aged 11 to 13 years old) participated in this study. In a crossover design, electroencephalography (EEG) was used to measure and determine the psycho-physiological effects of four different visual stimuli: an actual plant, artificial plant, photograph of a plant, and no plant. Subjective evaluations of emotions were assessed using the profile of mood state and semantic differential methods immediately after exposure to each visual stimulus. A significant decrease in theta waves of the frontal lobe was associated with presentation of the actual plants. This response indicated that the viewing of living plants prompted improvements in the attention and concentration of the elementary students. Furthermore, the presentation of the living plants was associated with more positive mood states, such as feelings of comfort and naturalness. In conclusion, actual plants may improve attention and prompt psychological relaxation in elementary students relative to artificial plants, photographs of plants, or the absence of plants.

Children in modern society are exposed to high levels of stress. Various previous studies have reported that horticultural activities help children's emotional stability. The objective of this study is to develop and implement a horticultural therapy program to improve the emotional intelligence, resilience, and self-efficacy of elementary school students. A total of 582 Korean students (11-13 years old) from 28 schools participated in this study. The horticultural therapy program consisted of seven sessions and was conducted once a week for 60 min per session, during regular or after-school classes. Before and after the horticultural therapy program, emotional intelligence, resilience, and self-efficacy of the elementary school students were assessed using questionnaires. At the end of the program, students evaluated their satisfaction with the program. The horticultural therapy program significantly improved emotional intelligence (p = 0.000), resilience (p = 0.001), and self-efficacy (p = 0.003) of the elementary students participating in this study. After the program, emotional intelligence improved both male and female students. In resilience and self-efficacy, male students improved after the program, but female students did not. This study may show a potential of horticultural therapy for psycho-emotional health of children.