The field road bunker gets its first trees

The small pine tree makes one more circle in the sun around the field road bunker before it is carefully lowered by the crane to the second level on the south-west side. Horticulturist and landscaper Tim Eddelbüttel and his helpers receive the coniferous tree and slowly lower it into the prepared hollow on sturdy belts.

The planting of the converted bunker on the Heiligengeistfeld has started with a total of three mountain pines and a columnar juniper. The trees, each about three meters high, 18 years old and weighing half a ton, are the first of a total of 4,700 trees and more than 16,000 perennials that are intended to green the various levels of the bunker built between 1942 and 1944.

It starts with the second level, the approximately 330 meter long "lower mountain path", which hotel guests will later look at. The level above is the ascent around the new building, this "upper mountain path" is about 230 meters long. At the very top, high above the roofs of Hamburg, a 1,400 square meter public city garden is planned. The planted mountain path leads along the outside of the bunker all the way to the top and ends at a height of 58 meters on the roof garden.

Depending on the weather and the progress of the construction work, a total of around 7,600 square meters are to be planted by the end of the year, or early 2023 at the latest. A "lighthouse project that is unique worldwide", as tree nursery owner Bernhard von Ehren, who supplies the plants, enthused: "After extensive preparation, it's finally starting." make".

In order for the evergreen plants to feel comfortable in the extreme location at dizzy heights, 2000 cubic meters of specially developed substrate with small lava stones were piled up, which has an extremely low dead weight but can absorb and store a lot of water.

The bushes, hedges and climbing plants that follow the trees in the next step were also specially selected for the demanding location. They are native to northern Europe and the Alps and, according to the experts, can withstand frost, heat and storms at heights of more than 50 meters.

These include fruit trees, Scots pines, service pear, Zoeschner maple, laurel cherry, holly, field maple, ivy and rose bushes. The larger trees, such as service pear and field maple, which are planned for the shady north side, will also be anchored underground to secure them against gusts of wind.

A sustainable irrigation and drainage concept is intended to reduce the amount of rainwater by a good 75 percent so as not to overload the public sewers. The entire project is scientifically monitored in order to understand the effects of greening on the building and the microclimate in the district. For this purpose, researchers from the TU Berlin have installed around 80 sensors throughout the bunker.

Since 2019, the bunker, which is one of the largest in Germany, has been expanded by five pyramid-like floors and is scheduled to be completed in the next six months. Inside there is space for a hotel and a hall for up to 2200 visitors. In addition, rooms for culture as well as a bar and a restaurant are to be accommodated.

A memorial and information center is also planned in the 80-year-old building, which was built in around 300 days using forced laborers: the victims of the Nazi regime and the Second World War are commemorated in the former control room and at other points in the existing building to be reminded.