This department carries out regular inspections of the city's tree population. It also takes care of the resulting maintenance and conservation measures for the trees, using its own staff and external contractors. If trees in the city's tree population need to be felled, the employees also coordinate the corresponding replanting. Based on the legal ordinance for the protection of the tree population of the state capital of Mainz, the department decides on approximately 200 felling applications in the urban area of the state capital of Mainz. The "Geschenkter Baum" (Gift Tree) campaign currently provides 75 garden owners with trees for planting and long-term care on their properties. Excavations on urban green spaces are also coordinated and agreed upon.

The department also includes the city nursery, where around 120,000 flowers are cultivated each year for the city's decorative flower beds, as well as shrubs and trees for its own use. In addition, the city nursery is a recognized training center where young gardeners are regularly trained.