Landscaping
The Arizona Department of Transportation allows placement of landscaping in the right of way provided the landscaping does not include anything that would be a hazard to the motorist.
Lists of allowable plants may be obtained by contacting the Permits Office.
To obtain a permit to place landscaping in the right of way submit a permit application and five sets of drawings showing what will be done in the right of way.
The application form and instructions are available here.