The Botanical Gardens were established in 1936 by The Niagara Parks Commission for the “Training School for Apprentice Gardeners” 9 km (5.6 miles) north of Niagara Falls. The Botanical Gardens site is the outdoor classroom for the students attending a unique 3­-year horticulture diploma program at the School of Horticulture. The training program is designed to give students practical experience by participating daily in horticultural activities. Under staff direction, the students work on the development of the Botanical Gardens and are responsible for its maintenance. As well, the students are responsible for maintaining gardens that include other Niagara Parks attractions such as the Floral Clock, Queen Victoria Park, Oakes Garden Theatre and the Floral Showhouse. The gardens opened to the public in 1937, and are open 365 days a The Botanical Gardens contain 40 hectares (100 acres) of beautifully maintained grounds.The Arboretum covers the largest area of the Botanical Gardens and contains collections of hardy woody plants, mainly trees. The arboretum contains one of Canada’s finest collections of ornamental trees and shrubs. The Gardens are designed for the collection and study of plants.Most of the specimens are labeled for the benefit of the students and visitors . The Botanical Gardens is home to a world­famous rose garden featuring over 2,400 roses. The greenhouses at the Botanical Gardens and Butterfly Conservatory consist of 1,800 sq. m (19,386 sq. feet) of combined space. The greenhouses allow students to learn about greenhouse management and serve as a classroom for interior plantscaping and other courses.Also on the grounds is the Butterfly Conservatory. The Niagara Parks Butterfly Conservatory is a butterfly zoo. The conservatory was opened in December 1999,and has over 2,000 tropical butterflies from over 60 different species. The conservatory glass dome is 1,022 square m (11,000 sq ft) in size with 180 m (590 ft) of paths inside the greenhouse portion, which has a wide variety of plants. Since captive butterflies usually have a life span of 2–4 weeks, the conservatory imports up to 3,000 butterflies per month from world butterfly farms. Butterfly food plants are replaced every 2–3 weeks because caterpillars have large appetites. The conservatory is home to native butterflies, such as the Monarch, Tiger Swallowtail, Painted Lady and Mourning Cloak.