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Sunday - September 04, 2011

From: New Braunfels, TX
Region: Southwest
Topic: Watering, Trees
Title: Watering practices for live oaks in drought from New Braunfels TX
Answered by: Barbara Medford


We have conflicting info about watering live oaks. An arborist says to water now using soaker hoses or small sprinklers and a landscaper who spoke to our garden club said that after August is too late to water trees even during a drought. Could you help us with this. Thank you.


We do not want to get in a difference of opinion with any of the people you have been hearing from on taking care of the live oaks during our heat and drought. All we can do is tell you what we think, based on the practices at the Wildflower Center and on our own observations.

First, we can't say that it is ever too late to water the roots of any tree during the kind of weather conditions we have been having for months. Whether or not the weather improves, the re-emergence, indeed the life, of those live oaks in the Spring depends on the roots continuing to have the moisture they need. The root are the conduits for water and nutrients, which go to the leaves, the manufacturing facilities of the tree. You probably already have leaves dropping from your live oaks, trees which ordinarily drop most of their leaves in March, quickly followed by new leaves. The leaves dropping now will not be replaced until Spring, but if the tree has no water in the roots to conduct the nutrients up through the vascular system, there will be no new leaves. That's a condition called DEAD.

As for the method of getting water to those roots, this depends, in our minds, on the age and size of the trees in question. A young new tree should still be getting the hose stuck down in the loose dirt around the trunk, and have a slow dribble of water until water appears on the surface, at least twice a week. This is effective at that point in the tree's development because that's where the roots are, still close to the trunk of the little tree. However, as the tree matures those roots are going out farther in their quest for water and nutrients. A pretty standard measurement is that a mature oak tree will have roots at least two to three times the circumference or height of the tree. In other words, far beyond the "shade line"  or dripline of the tree. A live oak is a much too valuable tree to waste the resources (money, time, water, etc.) that have already gone into it. We suggest a sprinkler moved from place to place around the root area. We would avoid depending on an automated sprinkler system; for one thing, spraying water on the trunk of a tree can lead to fungus infections or rot.


From the Image Gallery

Escarpment live oak
Quercus fusiformis

Escarpment live oak
Quercus fusiformis

Escarpment live oak
Quercus fusiformis

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