Biomedical instrument advancements have made it possible to record and understand human responses to plants in urban environments. Biofeedback is an experimental method used to measure stress by monitoring blood pressure, heart rate, skin temperature, muscle tension, and electro-dermal responses. Initial biofeedback research at KSU involved measuring finger tip temperature responses to interior plants while subjects listened to a relaxation tape. Within five minutes, subjects near a live plant had increased skin temperature and lower stress, while those looking at a photograph of the same plant were less responsive, and minimal change occurred in the same room with no plants. Another group of subjects, walking through a botanical garden had significantly lowered heart rate and blood pressure. Stress reduction occurred and fast beta brain waves increased for subjects in a room with red flowering geraniums as compared to responses in a room with green foliage or in an empty room. For groups of students who were gardening, within 40 minutes, significant changes in immunoglobulin A and cortisol occurred, as compared to those who were not gardening. This resulted in fewer colds and respiratory problems reported by the gardening group. Other KSU research has measured social interaction, stress, and pain perception to fragrance, color, and plant density within hospital rooms, classrooms, and landscape gardens.
Keywords: horticultural therapy, human bio-monitoring, health and wellness, stress reduction, human issues in horticulture