Sponge City for Urban Trees Sponge City for Urban Trees How to plant a tree in a smart and sustainable way? By loading the video, you agree to Vimeos’s privacy policy.Learn more Load video Always unblock Vimeo The Sponge City for Urban Trees aims to mitigate the climate impact in cities through a blue-green infrastructure based on the healthy growth of urban trees that are the best instrument to cool down the street and foster urban life. The project aims to implement the Sponge City concept in several Austrian cities by planting trees in streets and squares with a substrate that offers the trees about 30% of cavities where their roots can expand and where the water necessary for their consumption is retained. Urban trees are the air conditioning of the city; they are the key to the climate future of our cities.