Summer Tree Watering

For now, native and established trees don’t need any supplemental water. But should the weather turn particularly dry, they might. Just be sure to water them right.

Little did I know that when I first started writing this article we’d be inundated with rainfall…

I would’ve told you that established trees — those that have been in the ground for three or more years — seldom need supplemental water. I also would’ve said that if they did need watering at all, there is a correct way to do it.

As it stands right now, rain has been so plentiful that native and established transplanted trees will not require any supplemental water. Of course, there’s always the chance the weather will revert to hot and dry, dry, dry so you may need to give those established trees a little drink.

When that time comes, keep these things in mind:

  • The dripline of the tree is the key watering area. This is where the tertiary root — which does most of the absorption — is located.
  • When watering a tree, the emphasis is on infrequent and deep. Infrequent means once every 30 to 60 days in the absence of effective rainfall. If we have a “good rain” then supplemental water is not needed. Deep is a slow watering that penetrates the top 6 to 10 inches of soil. Generally, for our area this is 1 inch to 1 ¼ inch of water per application.
  • Applying 2 inches of mulch around the tree and beyond the dripline helps reduce the amount of supplemental water necessary. Mulch reduces water evaporation and cools the soil, which in turn encourages root growth. The more roots, the less supplemental water required. Trees that have been properly planted and established seldom need supplemental water.

Fortunately, this year the need for supplemental water appears to be little or none. We have had plenty of spring precipitation and our trees are well on their way to producing lots and lots of food.

Picture of Mark Peterson
Mark Peterson
Mark A. Peterson was a conservation project coordinator for San Antonio Water System before retiring. With over 30 years of experience as an urban forester and arborist, Mark is probably the only person you know who actually prunes trees for fun. When not expounding on the benefits of trees and limited lawns, you're likely to find him hiking San Antonio's wilderness parks or expounding on the virtues of geography and history to his friends.
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