No building or structures shall be permitted on the site with the exception of storage sheds, greenhouses that consist of buildings made of glass, plastic, or fiberglass in which plants are cultivated, benches, bike racks, raised/accessible planting beds, compost or waste bins, picnic tables, seasonal farm stands, fences, garden art, rain barrel systems, and children's play areas shall be permitted. The combined area of all buildings or structures shall not exceed 15 percent of the garden areas.