The park, like the castle, was undergoing various alternations, beginning with the original Italian garden which was changed in the 18-th century by Teofila Działyńska-Szołdrska-Potulicka into a then-fashionable French style park with trimmed hedges, artificial ponds, fountains and stone figures. The Arboretum was originated in the 19-th century, when Tytus Działyński started collecting trees and shrubs on an enlarged area while he was reconstructing the castle. The new landscape park was arranged in the English style, spreading meadows and lawns, broad views and random groups of trees and shrubs. This park up to this day keeps a lot of elements this old garden architecture.
After Tytus Działyński the Arboretum went into the care of his son Jan, who was a skilled and keen gardener-dendrologist. Meaning to organize in Kórnik „a botanical garden of a forest school”, he gathered an impressive collection of trees and shrubs, especially conifers.

Arboretum is now part of the Dendrology Institute of the Polish Academy of Sciences which is the greatest nature pride of Kórnik commune. Kórnickie Arboretum is one with the oldest and richest parks in number of species in Poland – it has about 3500 species and genera of trees and shrubs. Many specimens growing here, some quite enormous in size, are 130-180 years old. The 300-year old little-leaf linden trees are the oldest.
In the years 1960-1970 dendrological collections were extended on the areas east of the old park, and since 1970 some new species of trees and shrubs (especially rhododendrons and azaleas) have been planted in Zwierzyniec, the experimental wood area, located behind the Kórnickie Lake.