Located on the Gustaf-Gründgens-Platz, alongside the heritage-listed Düsseldorfer Schauspielhaus theatre, the five-storey office block topped out earlier this month.
When it is completed next year, the two main facades of the trapeze-shaped building will be covered with hornbeam hedges. Hedgerows will be installed on each floor of the building's slopped facades, spanning a total distance of five miles, or eight kilometres.
The building's roof will also be covered in greenery, to a planting strategy developed in collaboration with sustainable engineering firm Werner Sobek.
"From Gustaf-Gründgens-Platz the main building looks like a virtual 'vertical park' with eight kilometres of hornbeam hedges, the leaves of which take on different hues throughout the year," said Ingenhoven Architects.
The hedges have been growing at a tree nursery since 2016 and will be delivered to the site, complete with fully formed roots, later this year.
According to the architecture studio, the planted facade will help cool the building, reduce the inner-city heat-island effect in Düsseldorf, and help clean the air.
The 41,370 square-metre office block will stand opposite a smaller triangular building, which will contain restaurants and shops. It will be topped with a lawn that will be accessible to the public.
The office and retail buildings have been designed to frame views of the theatre.
"The two buildings of the new development, with their sloping facades, create a dynamic through-passage that opens the view towards the theatre," explained Ingenhoven Architects.
"The facade of the main building also slants towards the theatre – a gesture of deference to the listed building."
Kö-Bogen II is part of a growing trend of office buildings being covered with plants. CF Møller and Reiulf Ramstad are planning to build a plant-covered tower in Oslo, while Stefano Boeri is designing a tree-clad tower in Utrecht.
Boeri is also designing a tree-covered social-housing project in Eindhoven, plus Heatherwick Studio's 1000 Trees project is nearing completion in Shanghai.