Vegetation is a much appreciated element in our outdoor environment that has many advantages as well for the climate as for people's health. However in some types of environments vegetation may be problematic. Especially in urban areas with limited space, solid surfaces, pollutions, and warm and dry climate. In these environments vegetations may have difficulty surviving and moreover it may have a negative impact on the environment around it. It is also in these environments the most people are and so it is desirable to have as much vegetation as possible in these problematic environments. Therefore there is a need for knowledge of how we can integrate theses green elements in theses problematic environments in a sustainable and functional ...