Along each side or rear property line which directly abuts a residence district in the Township or a similar district in an adjoining municipality, a buffer planting strip, as defined in § 280-4B, of not less than 30 feet in depth, shall be provided. Along each street line bounding a residence district, a strip of land not less than 20 feet in depth shall be suitably landscaped except for necessary sidewalks and accessways crossing the strip.