Beuys's project 7000 Oaks was begun in 1982 at Documenta 7, the large international art exhibition in Kassel, Germany. His plan called for the planting of seven thousand trees, each paired with a columnar basalt stone approximately four feet high above ground, throughout the greater city of Kassel. With major support from Dia Art Foundation, the project was carried forward under the auspices of the Free International University (FIU) and took five years to complete, the last tree having been planted at the opening of Documenta 8 in 1987. Beuys intended the Kassel project to be the first stage in an ongoing scheme of tree planting to be extended throughout the world as part of a global mission to effect environmental and social change; locally, the action was a gesture towards urban renewal.
One of his projects, perhaps the grandest in scope, was 7000 Oaks. Begun in 1982, this ambitious project became a five-year effort in which he and others planted 7,000 trees of various types throughout the city of Kassel in Germany, each with an accompanying basalt stele as a marker. The solid stone form beside the ever-changing tree symbolically represents a basic concept in Beuys' philosophy, that these two natural and yet oppositional qualities are complementary and coexist harmoniously. Local community councils, associations, and citizens' initiatives determined where the trees would be planted. The organization of this project resulted in a series of conversations among participants concerning a wide range of issues, from its impact on city planning to its meaning for future generations. Completed in 1987 by his son, Wenzel, on the first anniversary of his father's death, 7000 Oaks truly epitomizes Beuys' ideas about art and its ability to effect change in society.