Plantings. All portions of a lot not covered by buildings or structures (e.g., parking lots, parking spaces, loading areas, access aisles, driveways, sidewalks, walkways, curbs, trash enclosures, children's play areas, dog walks, etc.) shall be suitably planted with grass, shrubs, and trees and shall be maintained in good condition. In any case, no less than 20% of the area of the lot shall be so planted, and the planted area may include approved detention and/or retention basins.