No person, owing or having charge or control or occupancy of any lot or private premises shall allow grass or weeds to accumulate or grow upon any abutting paved sidewalk area above its established grade or upon any part of said sidewalk area from curb to street line, provided, however, that nothing herein contained shall be construed to require the removal from the borders of any sidewalk of any ornamental plant, lawn, shrub, or trees of reasonable growth, provided that the same area not, in the opinion of the City Officer, obstructions to the free use of such sidewalk by pedestrians.