The currently persistent drought is already causing problems for the trees. 

In the event of prolonged drought, we recommend watering the trees as follows, depending on the soil conditions:

Trunk circumference 16-18cm: 150 litres of water per week
Trunk circumference 20-25cm: 250 litres of water per week
Trunk circumference 30-35cm: 350 litres of water per week
Trunk circumference 40-45cm: 600 litres of water per week
Trunk circumference 50-60cm: 1,000 litres of water per week
Trunk circumference 70-80cm: 1,500 litres of water per week

City trees have it particularly difficult when it is dry and also need our help in such extreme situations, even if they have been in their location for years.

"Freshly planted trees are particularly affected, because they need significantly more water than a tree that has already grown to grow well in the substrate."
– Hans-Albrecht Thrun, Nursery Lorenz von Ehren

Please water sufficiently and regularly, the trees will thank you with cooling and shade!