"Screen" means a neat, orderly and healthy screen of evergreen or other plant material suitable for the purpose intended, not less than three feet high with an expected normal growth to five feet in height, and, where necessary, protected by a galvanized wire link fence at least five feet high. A decorative wooden or masonry fence or other decorative material or landscaping may be substituted for the vegetation. Bumper guards or wheel stops shall be provided as necessary to prevent damage to a required screen or fence by automobiles.