The first plantings in the Arboretum were in the fall of 1889, when 200 trees and shrubs were planted for testing. By 1899, there were 3,000. At that time, little was known about the hardiness of exotic plants in the Ottawa area. Trees were obtained from nurseries in Germany, Japan, Korea, China, Russia, France, England and the U.S.A.

Many trees did not survive the Ottawa climate. Many did, however, and visitors to the Arboretum today are surprised to find specimens which normally do not grow in the National Capital area.