The city planner or designated representative is hereby authorized and empowered to notify the owner of any property required to be landscaped, or the agent, tenant, lessee or assignee of any such owner, that the landscaping is not being adequately maintained and the specific nature of such failure to maintain. The notice shall specify the date by which the maintenance must be accomplished, and shall be sent by certified mail, addressed to the owner at the last known address.

Upon the failure, neglect or refusal of any owner or agent so notified to perform the required maintenance within the time specified in the written notice, or within fifteen days after the date of such notice if the notice is returned to the city by the by the Post Office because of the inability to make delivery thereof provided the notice was properly addressed to the last known address of the owner or agent, the city planner or representative may take additional enforcement action as authorized by this title.