A landscaped area eight feet in width, measured inward from the lot line, shall be maintained, exclusive of driveways, on all sides of the property except where required to be wider by § 190-57; treatment shall be of grass, ornamental stone or evergreens maintained below 2 1/2 feet in height, except where required to be higher by § 190-57 and surrounded by curbing (wood, stone or concrete) four inches to six inches in height.