That is a very good question. The current ordinance states:
96.010 RIGHT-OF-WAY LANDSCAPING.(a) The portion of a dedicated public right-of-way between the street and the property line excepting the sidewalk shall be landscaped and maintained by the abutting property owner. Landscaping shall be limited to sod, seed or other living ground cover approved by the city. Nonliving ground cover, including, but not limited to, rock, stone, brick concrete, asphalt or other like materials, shall not be used as landscape material except as provided herein.(b) The city may authorize the use of nonliving ground cover for landscaping a public right-of-way when it is determined that a location will not allow for adequate maintenance of sod or other living ground cover. This exception shall not include the use of loose rock or asphalt as landscaping material.
(1992 Code, § 38-12) (Ord. 37-03, passed 5-5-2003)