Any part or portion of the site which is not used for buildings, other structures, loading or parking spaces and aisles, sidewalks and designated storage areas shall be planted with an all-season ground cover and shall be landscaped with trees and shrubs in accordance with an overall landscape plan as recommended by the Planning Commission and approved by the Board of Supervisors. All sites and parcels of land adjacent to a public street or dedicated service roadway shall maintain a landscaped strip adjacent to the right-of-way at least 15 feet. This area shall not be used for building, parking spaces, aisles or storage, and only approved driveways shall be permitted to be constructed on or across this strip. The right-of-way of any public street, highway, or service road shall not be used for any use incidental to the adjoining property.