Planting areas. All public off-street parking areas which serve five vehicles or more and are created or redesigned and rebuilt subsequent to the adoption of this chapter shall be provided with accessory landscape areas totaling not less than 5% of the surfaced area. The minimum size of each landscape area shall not be less than 100 square feet, and landscaped area shall be distributed evenly throughout the parking area. Location of landscape areas, plant materials, protection afforded the plantings, including curbing and provision for maintenance, shall be subject to approval by the Plan Commission. All plans for such proposed parking areas shall include a topographic survey or grading plan which shows existing and proposed grades and location of improvements. The preservation of existing trees, shrubs, and other natural vegetation in the parking area may be included in the calculation of the required minimum landscape area.