Stefano Boeri

For more than two millennia architecture has viewed buildings mainly as dead objects – immutable, frozen in time. Stefano Boeri’s vertical forest embraces change. With the leaves growing and falling, the look of the building is totally different in spring than in fall. Stefano Boeri: ‘As a child I was already obsessed with trees, their individuality, their form. Later, I imagined how trees could be the protagonists of a new architecture. There is a lovely tower in the small Tuscan city of Lucca, the Torre Guinigi. It was built in the fourteenth century and has trees on the top. I also found examples in the work of Emilio Ambasz from the 1970s that reconciled ‘gray and


One of my most visionary predecessors is Friedrich Hundertwasser, an enigmatic painter from Vienna who started to make ecological architecture in the 1960s. I remember him coming to Milan in 1972 – I was sixteen. One of the most impressive projects I ever witnessed was the ‘7000 Oaks’ project by Joseph Beuys at Documenta 1982 in Kassel. Beuys succeeded in altering the landscape and living space of the town by planting trees on a large scale. The idea to use trees as a material to transform, condition and shape the city was something new. Amazing! This example was extremely important to me. Beuys will always be a genuine master to me.’


Of course it took quite a while to convince a real estate developer to build the first vertical forest. In 2006 we were invited to propose our concept to Manfredi Catella, CEO of the Italian branche of the American Hines Company. He welcomed the idea, but he was also a bit sceptical about its feasibility. In a huge wind tunnel we tested the resilience of trees under extreme weather conditions. We calculated the long-term costs of maintenance. Together with Arup Structural Engineers we figured out the construction of the concrete slabs of the balconies to make them capable of carrying the huge weight of the trees. After a few months of testing we were given the green light. Finally, in 2009 we delivered our first Vertical Forest in Milan. An emotional moment.’ ‘The vertical forest is one of the most efficient ways of dealing with the effects of climate change and global warming in cities. Buildings that host thousands of trees on a very small surface really contribute to the reduction of CO2, which our cities produce in such large amounts. Trees also absorb the fine dust particles emitted by traffic, helping to clean the air. They protect from the heat and improve biodiversity, not only of vegetal species but also of birds. There are more than twenty species of birds that nest in the Bosco Verticale in Milan.’


‘When we study a new building site with the studio, we first start inventorying plants that are indigenous to the region and best adapted to the local climatological conditions. With the botanists in our team we discuss how a certain plant grows, how it occupies space and figure out how to orient it to make it grow and flourish best. Then we plan the space for the trees, plants and shrubs on the balconies. In Northern Europe we choose plants that loose their leaves during wintertime, letting sunlight flow into the apartments. Meanwhile, in Africa we choose plants that hold their leaves the whole year around.’


‘There are currently vertical forests under construction in three Chinese cities: Liuzhou, Shanghai and Huanguanq. We are also building in Utrecht, Eindhoven, Tirana and starting in Caïro, Antwerp, Mexico and Treviso. In the coming months fifteen new vertical forests will open all over the world. In the meantime we constantly develop new insights and solutions. For example, the building in Utrecht differs very much from that in Eindhoven. In Utrecht there is a complex of functions: commercial spaces on the ground floor, offices from the second to the tenth floor and apartments for middle and higher incomes. In Eindhoven we are building social housing and so we had to learn how to keep costs low. That makes the concept more democratic.’

living nature

‘I see myself as a pioneer in using trees as components of a building. Architecture has always used natural materials to construct buildings. By introducing living nature into it, the practice of architecture changes and hopefully also its future perspective. Fortunately, many architects are now following our example.’

This interview was published in WOTH issue No15 still available in our shop.