Vegetation must be maintained and kept healthy for two years through at least two growing seasons. A maintenance guarantee specified by the City as acceptable shall be provided by the developer/owner for landscaping required by the City for any development project. The maintenance guarantee shall be in an amount equal to 20 percent of the total landscape construction costs and shall be in effect for at least two full growing seasons (March through October). The developer/owner must provide this landscape maintenance guarantee to the City at the time of final inspection of the development project.