• Tips for applying the right amount of water
• The right amount of water
• The moisture content of the soil
• Adjusted watering requirements
• Watering table

- as a rule of thumb, we use approximately 30 litres of water per centimetre of trunk circumference per week for a single-stemmed tree

- if a tree has a trunk circumference of 20 cm measured at 1 metre height, the amount is 20 x 30 litres = 600 litres per week

- use this on a weekly basis: water 3 times a week, with two days in between without watering

- in the above situation, you would give 200 litres 3 times a week

- the amount of water to be given is strongly influenced by the depth of the groundwater level and the amount of rainfall

The amount of water given per watering depends on the site conditions and a number of additional factors. Soil type, sun, shade, wind and paving all have a strong influence on the amount of moisture that evaporates and therefore needs to be replenished. Factors to consider include the duration of the drought, the average temperature and the type of soil. The size of the tree, the crown volume and the method of watering also play a role. As a rule of thumb, we use approximately 30 litres of water per centimetre of trunk circumference per week. With each watering, the essential point is that the water reaches the roots and that the tree has time to absorb the moisture. It is also important that the water does not run away from the root ball, but remains around it so that it can soak into the soil. A raised rim around the tree or a plastic watering rim is necessary for this. Watering also cools the root ball and can slow root development. To prevent this, it is better not to water daily, but for example once every 5 to 7 days. As long as the soil remains slightly moist, it is much more able to absorb moisture again. Once the soil has dried out completely, it takes a very long time before its moisture-absorbing capacity returns. With this in mind, it is better to give one substantial watering per week than several small amounts throughout the week.

In general, the following amount per tree per watering is recommended.

16-20 cm circumference 100-125 litres
20-30 cm circumference 125-150 litres
30-50 cm circumference 150-250 litres
50-70 cm circumference 250-500 litres
70-100 cm circumference 500-750 litres

A good way to check whether watering is needed is simply to assess the moisture condition of the soil. Take a handful of soil from the root ball at a depth of approximately 15 cm. If the soil feels very dry and breaks apart into dry particles, water should be given. If the drought continues and watering is delayed, the leaf margins will start to curl and yellow-brown edges will appear. If the soil can be squeezed into a ball, the moisture level is correct. If water comes out of the soil when squeezed, the soil is too wet and there is a risk of decline caused by root rot; if this continues, it will show as yellow discolouration of the leaves. The symptoms of trees that are too wet are very similar to those of trees that are too dry. The pattern is, however, the reverse: in the case of drought stress, the leaves wither from the outer edge of the crown inwards. In the case of soil that is too wet, the pattern is dieback from the centre of the crown outwards towards the outer edge. Trees growing in paving require more supplementary watering than trees in more natural conditions, such as in a planting bed, possibly even after three growing seasons, so take this into account during aftercare.

For a number of tree species, it is advisable to pay extra attention to proper watering. Take, for example, a newly planted yew hedge in spring: the plants have a relatively small root ball and a great deal of foliage. They therefore lose a lot of moisture and struggle during a dry spell in spring, especially in combination with a dry wind. Desiccation is then a real risk. In any case, it is advisable to give evergreen species extra water during the first months after planting. During a dry period, it may also be advisable with conifers to spray water over the crowns towards the evening, so that moisture loss through the needles is reduced.