August 24, 2023 | by shivam saxena

An experiment in using living plants to grow structures reminiscent of the way farmers, horticulturists and gardeners  have trained plants and trees for shade structures and hedges for centuries – Baubotanik.org have a new look at this ancient technique:

Baubotanik: German architects develop project on building botany


The future of dwelling is alive. That is the belief of three young German architects from Stuttgart who are banking on a completely new building support structure—plants firmly rooted in the soil. In this way, houses and cities could literally grow into the skies. They have already created Baubotanik, or ‘building botany’, bridges and pavilions. 


If it were up to Ferdinand Ludwig, mankind would one day again live in trees. The Stuttgart architect dreams of roofs and walls that consist largely of living ash, poplar and plane trees, firmly rooted in the soil. Whole forest-cities could then reach into the skies, cities whose leafy houses could, moreover, contribute to purifying the air.

Building castles in the air? Not quite, since Ludwig, together with Oliver Storz and Hannes Schwertfeger, forms the core of the research group ‘Building Botany-Living Architecture,’ or ‘Baubotanik’ at the University of Stuttgart in Germany.

The three Ph.D scholars are the founders of a new architectural discipline, in which irrigation systems and hedge clippers take the place of plumb lines and trowels. Ludwig is in charge of biology and botany, Storz of the engineering and construction aspects, and Schwertfeger of the architectural theory.

Ludwig wants to develop a technology to construct living architectural structures in the dimension of a fully grown tree.  “Liveable houses made of trees are possible. They are our declared long-term goal,” says Ludwig.


When bridges grow roots


“Actually, we’re not utopians”, says Ludwig. “We only want to explore what is possible when trees are re-thought as building support structures.” What has been possible up to now can already be seen in numerous projects. Ludwig tells the German Information Centre, “When we started the project most people were quite sceptical, and many still are. But with the first successful projects, like the living skywalk, more and more people were interested in the work and step by step a new kind of research combining architecture and biology emerged.”

The first masterpiece was a twenty-metre long bridge in a moor landscape at Lake Constance, where a classical support structure would not have been possible. Now there are also two pavilions, a bird-watching house and five prize-winning information towers on the island of Mainau.

The bird-watching houseThey are constructed from thickly planted willow—from plants, that are well rooted, particularly thin, grow extremely rapidly and can be readily bred from cuttings. The plants, which grow high and crosswise, form a stable meshwork. The bird-watching house is the first botanically constructed building with a roof and more than two storeys. Up to ten hobby ornithologists can observe birds from its nearly two-metres high, 800 kilogramme platform.

Intelligent willow


For Ludwig and his colleagues, plants are “more intelligent” than brick and concrete. They like to speak of “constructive intelligence” when talking about the evolutionarily developed advantages of their architecture. “Plants have learned to carry heavy loads”, says Ludwig.

Their growing process optimises force and tension, and by contrast to technical building components, they have no predetermined breaking-points. “Moreover, wood thickens at those points where it is heavily stressed”; the architects therefore train their building material to form knots at crucial supporting points by deliberately exposing it to strain. In contrast to classical building construction, where materials gradually become brittle with stress, a living building literally grows with its tasks.

Asked about the difficult task of merging the precision of architecture with the spontaneity of nature, Schwertfeger says, “spontaneity is based on a specific point of surprise and we love and adapt to these moments. Nature is mainly a question of experience. In Baubotanik, precision as planning, function, and, not to forget aesthetics, is more a question of science and acting as a gardener. It is difficult to draw an absolute line between nature and intellect, between botany and architecture.”

In their projects, the three architects also use non-living technological materials. For instance, the bridge at Lake Constance is held together by polyester bands and reinforced by a stainless steel grid resting on a supporting structure of sixty-four bundles of withy. The bird-watching house is stabilised by iron rings. Altogether, the architects are concerned philosophically with a symbiosis of nature and artificiality. In Schwertfeger’s view, their buildings are “artefacts and living beings alike”. And as a matter of fact, nature vigorously continues building after the apparent conclusion of construction.

When does nature take over as the builder? Storz remarks, “The more you set on the growth of trees —the bigger and more complex you want to build the more you have to set on the growth—the more nature is predicting the rules that you as an architect have to accept. After you have finished the building site, the trees start their design process on your building. You can guide this process by cutting the trees. But in the end, you can just influence it so that it develops in a direction you want. You will never be able to design it exactly like you want. There are quite strict limits of control.”

Wildly exuberant surprises are as much desired as is the circumstance that the buildings look different in spring than they do in winter. “Our bridge”, says Ludwig, “can hardly be made out in summer for all the leaves”. Then the architects come again with their hedge clippers so as to cut open a passable area. Hannes Schwertfeger adds, “The motivation to work with growing organisms like trees comes from a vision of architecture, which is rather one of becoming, than one of being. So we have to adapt our requirements and aesthetic expectations to the growth and decline of a tree.”

The three architects have already developed a building botany willow pavilion ready for the market. It can be ordered for the home garden on the Internet. As their next projects, Ludwig, Storz and Schwertfeger are planning two pedestrian bridges with a span of six metres in the Saarland, and a twenty-metre long bridge over the river Neiße on the German-Polish border. But river-crossers will have to bring with them a natural degree of patience; in order to develop optimally a stable supporting structure, plants need time. The planned Neiße bridge will need seven years before it is fully grown.

On the other hand, plant buildings have a natural and not always calculable half-life. They can fall ill and die. A tree-house seldom survives more than a generation of inhabitants. Then worms, woodlice, fungi and bacteria would see to waste disposal, and wreckers would become unemployed.

Immortality and permanence aren’t, however, what these young architects are aiming for. On the inevitable death and decay of the system Oliver Storz tells the German Information Centre, “Actually this is the point that makes Baubotanik interesting and gives it legitimacy as a new aspect of architecture. Normally architecture is very static. It is built to stay there for a long time.

The longer the better, best if it’s forever. And every thing is done to keep it in the original condition. This is the first time a process is part of the architecture that changes it all the time—through the years, and also through the seasons; by the users and by the care, or by not caring. Baubotanik converts architecture to a process-based event. The death of the whole system is also a necessary part of this event.”

While they continue to hone the system, Schwertfeger, Storz and Ludwig are happy to aim even higher. Ludwig says, “With a prototypical tower, which is being constructed at the moment, we could show that it is possible to construct three-storey high tree-structures with very small, only several months old plants, by adding one plant on top of the other.


Employing this technology, it could be possible to quickly construct ‘high rise parks’ with aesthetic and ecological qualities of trees which normally take decades to develop.” Hannes Schwertfeger expresses interest to build within other cultures and also to get more experience with other kinds of plants. But he adds, “Baubotanik is not a simple and cheap way of constructing and doing architecture. We would need to have a good network, including scientists and, not the least, time.”


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