Glenn is a registered landscape architect in Florida, Georgia, and Texas, and has been in practice for over 20 years before joining the faculty of the University of Florida. His practice involved the design of new towns and new communities from their inception to the detailed design of specific sites. Glenn currently serves as consultant to the St. Johns River Water Management District for the design of water conservation demonstration projects. He also served on the national task force to assist in the preparation of the National Association of Home Builders’ New Green Design Guidelines.

Glenn's research focus includes:
• Documenting sustainable land planning and site design criteria
• Preparation of case studies in sustainable land development projects in Florida
• Water conservation through landscape and site design
• Integration of sustainable site design within land development and landscape codes