Due to its small size of two hectares, the open-air area of the Botanical Garden did not offer any potential for the development of a representative stand of trees and shrubs. As part of the plans of establishing a campus university that had been under consideration since the 1920s, a separate Arboretum was founded in the Friedrich-Ludwig-Jahn-Straße on the new University campus in 1934. It is about three kilometres away from the historic greenhouse and open-air area in the Münterstraße. The garden section was extended in the 1960s and in 1972.
Today, many wooded areas can be explored on a 3.5-kilometre-long network of paths. The trees and shrubs are planted according to their region of origin. The sections for the major regions of North and East Asia, Europe and North America show over 1,600 tree and shrub species. Special quarters present gardening cultivated and bred forms as well as local forest populations.