Other provisions of this chapter notwithstanding, in any district, the entire lot, except for areas covered by buildings or surfaced as parking, recreation or service areas, shall be seeded, sodded or planted with ground cover and suitably landscaped to include trees, shrubs, edging materials, stones, rocks or gravel in accordance with an overall landscape plan consistent with the natural surroundings. All landscaping shall be properly maintained throughout the life of any use on said lot. No more than 25% of any front yard setback landscape treatment shall include stones, rocks and/or gravel. All stones, rocks and/or gravel shall be placed over filter fabric, and any use of plastic or other impermeable material as a weed barrier is prohibited. Landscaping stones shall only be permitted if they are enclosed by four-by-four railroad ties or other comparable and suitable materials to prevent the stones from getting onto the sidewalk, curb, driveway and gutter area.