The provision of urban green spaces is becoming increasingly important due to the declining living conditions in cities. However, the demands of young people and adults often vary considerably and are not well understood. Furthermore, there are deficits in the participation of children and young people in urban planning, although their involvement in the relevant processes is becoming increasingly important. One of the reasons for this is the specific involvement of young people in citizen science initiatives. The u3Green project addresses these challenges by following the citizen science co-creation approach.