In nonresidential zoning districts, except for nurseries, garden supply, building supply, custom crafting, and similar businesses which require outside storage of materials, storage and display of materials outside a completely enclosed structure shall not be permitted. In the case of nurseries, garden supply, building supply, custom crafting, and similar businesses, outside display and storage areas shall be completely enclosed by an opaque fence or dense, compact evergreen hedge which is at least six feet in height.