Rebecca L. Haller, HTM, has practiced and taught horticultural therapy since receiving an MS in horticultural therapy from Kansas State University in 1978. Currently the director of the Horticultural Therapy Institute in Denver, Colorado, Ms. Haller teaches horticultural therapy classes in affiliation with Colorado State University, delivers workshops, and provides consultation to new or developing programs. At Denver Botanic Gardens, she designed and taught a series of professional courses in horticultural therapy, managed the sensory garden, and created programs and access for people with disabilities. She established a vocational horticultural therapy program for adults with developmental disabilities in Glenwood Springs, Colorado, which is still thriving after more than 30 years in operation. She has served as president, secretary, and board member of the American Horticultural Therapy Association (AHTA) and has worked on teams related to education and professional standards. In 2005, she received the Horticultural Therapy Award from the American Horticultural Society.

Awards from the American Horticultural Therapy Association include the Publication Award in 2009 and the Rhea McCandliss Professional Service Award in 2015. She has authored articles and chapters in the following publications: HortTechnology, Horticulture as Therapy: Principles and Practice, Horticultural Therapy and the Older Adult Population, Towards a New Millennium in People-Plant Relationships, AHTA News Magazine, The Public Garden, Acta Horticulturae, and Outdoor Therapies: An Introduction to Practices, Possibilities, and Critical Perspectives. She co-edited and wrote chapters in The Profession and Practice of Horticultural Therapy. Christine L. Capra, BA, is the program manager at the Horticultural Therapy Institute in Denver, Colorado. She and her colleague, Rebecca L. Haller, HTM, co-founded the institute in early 2002, which continues to offer accredited horticultural therapy education to students from across the United States and abroad. Previously, she worked as the program coordinator at the Denver Botanic Gardens' horticultural therapy program.

She has a BA in journalism from Metropolitan State University in Denver. Ms. Capra has written for numerous publications including OT Weekly, Mountain Plain and Garden, Green Thumb News, People-Plant Connection, AHTA News, GrowthPoint, The Community Gardener, Health and Gardens, Colorado Gardener, Our Sunday Visitor, Making Connections (Horticultural Therapy Institute Quarterly Newsletter), and Jardins. She co-edited The Profession and Practice of Horticultural Therapy. She was a reporter for the Denver Catholic Register newspaper for many years. She has received writing awards from the Society of Professional Journalists, the Catholic Press Association, and the Colorado Press Association. In 2009, she was awarded the Publication Award from AHTA.