Landowners shall be responsible for proper maintenance and care of all landscape treatments approved by the Planning Board. The Town's Code Enforcement Officer is authorized to inspect periodically all landscape treatments, including screening, as approved buy the Planning Board or to investigate complaints made by any official or private citizen concerning the maintenance of such landscape treatments. If completion of required landscape work is not practical due to seasonal or weather conditions, the applicant shall submit assurances to the Town Building Inspector for the completion of landscaping. The acceptable assurance guaranteeing the completion of landscaping shall be an irrevocable letter of credit, certified check, performance bond, or other acceptable assurance, equal to due cost of the landscaping work, accompanied by written assurance that such landscaping shall be completed in accordance with an approved site plan within a specified period of time, not exceeding six months from the date of occupancy.