Drought and heat devastate botanical gardens across Baden-Württemberg, killing trees planted for climate research

Freiburg and Ulm: trees dying in real time

The heat and drought across Baden-Württemberg have left visible damage in botanical gardens throughout the state. At the University of Freiburg's Botanical Garden, director Michael Scherer-Lorenzen described the situation as beyond strained. Past drought summers have been surpassed this year in both the length of the dry period and the heat load. Areas around some trees had to be closed to visitors because large dry branches broke off, and several trees will not survive the summer.

The situation is not only tense, it is actually already catastrophic.

He added that parts of the garden already look like autumn. At the University of Ulm's Botanical Garden, the situation is similarly tense. A head gardener reported that one can almost watch the trees dry out. The 28-hectare site cannot be watered comprehensively. Fruit trees are bearing fewer and smaller fruits that drop prematurely, and both deciduous and coniferous woody plants show early leaf loss and increased dead wood.

It partly looks like autumn.

Among those at risk in Ulm are 240 young trees planted as part of a climate change experiment, the very trees on which scientists intended to study resilience to climate change.

Tübingen and Stuttgart: rare species under threat

In Tübingen's Botanical Garden, trees are also losing leaves. Two Himalayan tear pines had to be felled due to a fungal disease worsened by drought damage, according to a garden spokesperson. The Alpinum, home to rare mountain plants, is especially affected, as these species cannot cope with the extreme dryness. The garden is shifting long-term toward more drought-resistant species such as Mediterranean plants, succulents, and frost-hardy cacti.

In Stuttgart, the Wilhelma manages not only its own park but also state-owned grounds including Rosensteinpark and Schlossgarten. A spokesperson said the tree stock there is under observation, with young trees planted in the past three years particularly endangered and requiring regular watering.

Heilbronn and Mainau: adaptation underway

In Heilbronn's Botanical Orchard, fruits are falling prematurely from trees. The city said that without regular watering of the perennial beds, there would be massive losses. Fruit trees and lawns are not watered, as this is not financially or personally feasible. Mulch is being used to reduce evaporation.

On Mainau Island in Lake Constance, the approach is long-term adaptation. Pronounced dry periods are no longer regarded as exceptions but as part of a permanent climatic shift, according to the garden. The historic woody stock is being protected with drip irrigation and automated systems, while new species and planting concepts better suited to heat and drought are being tested.

A forced rethink

What unites all the gardens is that the drought is forcing a rethink. More cisterns, water-saving irrigation technology, and climate-adapted plant selection are on the agenda. Botanical gardens will likely look different in the future than they do today. However, the funding for these measures is still lacking in many places.