Vertical tree care: a plant-covered building in Milan

An arborist crew fully equipped by PETZL will provide tree care to the vertical forest of "Bosco Verticale," the green architectural complex installed on the facades of two city towers inaugurated in Milan last October. This genuine adventure within the Lombard capital city caught the eye of both journalists and curious onlookers. Renato Comin, who is part of the tree care crew, talks about the specificities of this unique worksite.

"Bosco Verticale" was installed on the façade of two residential towers designed by Boeri Studio. The first building is 111m high (27 stories) and the second 78m high (19 stories). It forms a vertical landscape of hanging gardens: more than 700 trees and 4300 shrubs and flowers on the two buildings epitomize the concept of an urban vertical forest.
Located in downtown Milan, the structure is part of the PORTA NUOVA Project, which seeks to restore the historic ISOLA di MILANO quarter. The area's future already is already looking bright: in November 2014, "Bosco Verticale" won the International Highrise Award, the prestigious biennial international competition that rewards the world's most striking skyscraper. The building complex in Milano was chosen among 800 high-rises and skyscrapers across the world's continents.

The plant-covered work needs regular upkeep that requires specific skills in tree care and rope access. Two types of tree care operations have been established for this purpose.

The specific nature of the worksite

For Renato Comin, "What is certain is that in the beginning this was absolutely new for all of us, even though we have more than 25 years of tree care experience. Moreover, working on the side of a building adds a component that goes far beyond simple tree care, requiring rope access skills and special anchors on top of each structure.
We spent a first test week working with a three-person crew, and then employed a five-person crew for the following two weeks. In the end, we chose to work vertically instead of horizontally. This method is safer. Each crew member, every day, conducts tree maintenance as they descend. We also have put together a complex action plan specifying the exact time of day we will be working on each floor and how long the intervention will take. It has not been easy."

Combining plant architecture and safety...

"Bosco Verticale" is made up of different species of trees. There are ash, beech, olive, and evergreen oak trees to name a few. Even though they could grow much larger, these tall-trunk trees must be trimmed to remain no more than 8 to 9 meters high. Each tree grows in a reinforced box planter that is only one-meter deep. Closely monitoring their growth guarantees their stability. "This is not a haphazard operation," reassures Renato Comin. "At the outset, a detailed study on irrigation techniques was conducted to allow the plants to develop a dense and solid root system."

For safety measures, the building is equipped with wind-resistant anchors to ensure that plant care and monitoring stay on schedule. 

How does one enter the profession?

"I have a climbing and vegetation clearing background, even though I have been working in arboriculture for 23 years. One of our crew members is an experienced caver and climber, another colleague recently started climbing as well. The two other crew members have only worked in tree care."

"Over the course of my training, I started to specialize. Some of us have been true pioneers in the profession, and I am actually part of a group that worked to make proper instruction a requirement. When it comes to learning tree care techniques, I was lucky enough to experience first-hand the moment when ornamental arboriculture from abroad was adopted in Italy. This was in the nineties. During this period all of the textbooks we studied were in English since nothing had yet been written in Italian. Our specialty is now recognized at the European level, and to become certified you need to take exams on subjects such as tree care safety protocols and biology, among many others."

And PETZL in all this? 

"We contacted PETZL because the company's gear represents a real guarantee for us. Their equipment is not only the best on the market but also offers a great price/quality ratio. The weird thing is that I have to use an XS harness instead of the usual size medium. In general, rope access professionals are known to be stout muscular individuals, so this style of harness was obviously designed for them. I, however, am much smaller in stature."

The two towers overlook a vast public park known as "Porta Nuova Gardens" and also enjoy beautiful views of "Castillia Gardens," an 8000m² green space ideal for walking, playing, or simply relaxing.