It shall be the duty of the Commissioner of Street Sanitation
to cut down or cause to be cut down all overgrown weeds, grass, brush
and other vegetation on City-owned vacant lots and to remove or cause
to be removed all garbage, tree limbs or other debris on City-owned
vacant lots, in each and every year between May 1 and June 1 and as
often thereafter as necessary to maintain such lots in a sanitary
and orderly condition.