Before the expiration of said year, the administrative officer (Zoning Officer) shall, upon his initiative or upon the request of the organization theretofore responsible for the maintenance of the open space, call a public hearing upon 15 days' written notice to such organization and to the owners of the development to be held by the administrative officer (Zoning Officer), at which hearing such organization and the owners of the development shall show cause why such maintenance by the City shall not, at the election of the City, continue for a succeeding year.