Whenever a parking area is located in or adjacent to a residential district or property used for residential purposes, it shall be effectively screened on all sides which adjoin or face any property used for residential purposes by an acceptably designed wall, fence, or planting screen. Such fence, wall, or planting screen shall be not less than four feet (4 ft.) nor more than six feet (6 ft.) in height and shall be maintained in good condition. The space between such fence, wall, or planting screen, and the lot line of the adjoining premises in any residential district shall be landscaped with grass, hardy shrubs, or evergreen ground cover and maintained in good condition. In the event that terrain or other natural features are such that the erection of such fence, wall, or planting screen will not serve the intended purpose, then no such fence, wall, or planting screen and landscaping may be required.