D.C. Mun. Regs. tit. 24 § 102
The public parking on streets and avenues of the District of Columbia shall be under the immediate care and keeping of the owners or occupants of the premises abutting on the public parking.
No person shall use any parking for the purpose of drying clothes or other laundry.
No hedges shall be planted on public parking without a permit from the District. The same fee shall be charged as for parking fences.
Hedges on parking shall not exceed three feet (3 ft.) in height, nor project more than six inches (6 in.) over the sidewalk. On corner properties, if hedges are placed at the back of the sidewalk, they must be planted not more than ten inches (10 in.) above the sidewalk grade.
The Mayor is authorized to issue permits, without charging a fee, to erect tree markers of concrete or stone in tree spaces. The markers shall not be less than six inches (6 in.) nor more than eight inches (8 in.) square, or in excess of eight inches (8 in.) in height. They shall be driven firmly into the ground, and placed as directed by the Director of the Department of Public Works.
No tree marker shall be placed between a tree and a corner crosswalk. A metal plate may be placed on the upper surface of each marker, if it bears appropriate inscription and is securely fastened.
No person shall deposit or cause to be deposited any dirt, grass, or other yard refuse on any public sidewalk, tree space, roadway, or alley, from any public parking under the immediate care and keeping of the owner or occupant of the premises that abut the sidewalk, tree space, roadway, or alley.
D.C. Mun. Regs. Tit. 24, § 102