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Watering city trees | why it’s so important & how it works properly

Dry and hot summers will become more frequent due to climate change. In the particularly dry regions, not only the city dwellers suffer from drought. Also the city trees and other vegetation have a heart time during long-lasting heat. This can lead to so-called drought stress. Young trees in particular, which do not yet have deep roots, run the risk of dying of thirst. We show you why it is so important to counteract this and to water the trees during the hot season. And we’ll give you a few tips, links and hints so that your watering really does have an effect.

BUND calls for watering trees (Source: bund-berlin.de)

Why do we need trees in the city at all?

Urban trees fulfil several very important tasks. On the one hand, they are an important habitat for a wide variety of animal species such as birds, small animals and insects. And they do this from the roots to the tree trunk to the tree crown. They provide shelter, food and nesting opportunities for them, which are increasingly endangered in cities. Their importance for our urban ecosystem should not be underestimated. Insects in particular are central to the preservation of our urban flora and fauna.

On the other hand, urban trees function like urban air conditioning systems. They filter pollutants from the air (among other things, they bind enormous amounts of CO2), cool the environment with their shade and at the same time protect the soil from further drying out. This makes them an increasingly important form of protection against the backdrop of ongoing climate change.

At what point do our trees need extra water?

During dry periods that last longer than a week and are also exceptionally hot, it is already worth looking out for thirsty trees. You can recognise dry trees in most cases by drooping and brown leaves or by the fact that they drop their fruit prematurely. But even if the tree does not yet show any signs of drought stress, it is happy about every sip of water. So it is better to water once too often than too little!

How do you know which trees to water?

Screenshot of the giessdenkiez app

The most useful and sustainable approach is to find one (or more) trees in your immediate surrounding and take care of them regularly. Be it in front of your house, on your way to work or during a walk. Young trees in particular are dependent on sufficient water during dry periods, as their roots are not yet deep enough and they do not yet have large reserves.

Apps such as giessdenkiez (for Berlin) or giessdeinviertel (for Leipzig) now provide comprehensive interactive overviews of all urban trees, including information on their species, age, name and water requirements. Here you can find out which trees need water. And you have the option of registering and “adopting” a tree, whose watering you then take care of.

Many cities and municipalities – such as the city of Cologne or the city of Frankfurt – actively call on their citizens to support them by sponsoring trees and distributing so-called watering bags, which can be used to water the city trees sustainably. To find out if your municipality or city offers such a service, do an online search for “watering trees + city”.

What should you look for when watering trees?

In a drought, 1-2 watering cans a day already help a tree. Even if this is not always possible in everyday life, 8-10 buckets of water once a week (i.e. 80-100 litres depending on the size) would be even more sustainable. This way the soil around the tree is soaked for longer and it can draw water when it needs it. It is best to water slowly and wait until the water has seeped away before adding more. This way more water gets deep into the soil.

The most suitable time of day is early morning or late evening, so that the liquid does not evaporate again immediately due to the heat.

If you have the possibility to get rainwater or well water (for example via a public pump), then you should use it. After all, clean drinking water is not free and is a finite resource. Of course, you can also use regular tap water for a few buckets per week.

Watering city trees together is even more fun

Watering trees together can also be a nice activity with friends or neighbours. Simply put up a notice in your house and find people who would like to join you in watering trees. Here you can find a template (in German) that you can use, just download it, print it out and hang it up in your house.


Gruppenbild der vostel Mitarbeiter*innen auf dem Tempelhofer Feld

Your vostel.de team wishes you lots of fun watering city trees!


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