By Susan Motander
With California’s drought in its fourth year, the state has mandated water conservation. As a result, cities are being forced to impose restrictions on water usage. Michael Monte is an arborist for the city of Monrovia and has some suggestions regarding watering, especially the correct ways to water trees to ensure their health.
His first suggestion is quite simple: “If you are looking for ways to save water – hand water rather than relying on a sprinkler system. This way you water only what needs watering. If something is already wet, you won’t re-water it,” Monte said.
The city has mandated that sprinkler systems be used no more than 15 minutes every four days and that watering can only be done before 8 a.m. or after 6 p.m. Watering cannot be done within 48 hours of measurable rainfall.
That said; the question is how to water trees to ensure their continued health. According to Monte, watering differs greatly depending on the age of the tree. Established trees need water far less frequently than young ones. Only “minimal irrigation” is need for established trees. This means deeply soaking the tree for approximately half an hour to 45 minutes once a month. This needs to be done only during the growing season.
Young trees need to be watered every two to three weeks, again for an hour at a time. This deep soaking for young or established trees should not be at the base of the tree, but rather at the “drip line” – the area where rain water would hit the ground around the tree. This is normally around one, two or three feet away from the trunk depending on the size of the tree.
Asked to define deep watering, Monte explained that this mean the water should be barely dripping onto the area around the tree or by using a soaker hose (one with perforations that allow the water to soak into the ground).
Trees must be allowed to dry out completely before re-watering. Failure to do this could result in a soil fungus developing. This is especially true of oak trees. This fungus can severely damage or kill the tree.
Monte also explained that deep watering leads to deeper roots whereas surface watering encourages surface roots instead. Deep roots anchor trees more firmly to the ground; they also help trees to survive droughts.
