Most homeowners realize the need for watering trees in the growing season. However, it’s just as important during the winter months, defined as October through March in the arboricultural community. Drought effects on trees can take up to 5 years to show.  As much of our state suffered from Abnormally Dry conditions during 2015, we can expect to see water-starved trees exhibiting drought symptoms through 2016 and beyond.

Here’s what happens.

Due to excessive heat, water evaporates quickly. Trees lose some of their absorbing roots. These roots are the ones charged with exploring the soil for water, stretching out 2-3 times longer than the height of the tree.

Significantly, in a drought stressed tree, the roots begin to die because they can’t find water. The root system begins to contract. Once winter hits, a tree will lose vigor unless water is added to the soil.  Left unchecked, the tree could lose enough root tissue that by next spring, it’s unable to fully feed itself.

By analogy, the tree leaves act like the radiator of a car. The soil acts like the water reservoir. If the reservoir is empty it can’t replenish the radiator. If you don’t have enough water in the radiator, the car will begin to over heat and eventually destroy the engine.

With a tree, if the water in the soil – the reservoir – isn’t replenished, the tree’s “radiator “, the leaves and canopy, overheats, dries up and destroys the energy transfer engine.

But a tree doesn’t stop there. Consider if your car compensated for a lack of water by shrinking its radiator capacity to better distribute the water it did get.  Cars aren’t that smart (yet)- but trees are. They have the ability to shrink capacity to protect vital functions. Unfortunately, once the tree switches into survival mode, that means it stops growing and cuts off energy to the crown. This protective process comes at great cost, as the tree may no longer have the capacity to hold enough water to keep itself thriving or even alive.

How to Water your Trees

1.  Most of the tree’s absorbing roots are in the top foot of the soil. In well irrigated soil you can drive a screwdriver or spade 4 to 12 inches below the surface. In dry soil you are lucky to get  1 to 2 inches deep.

2. During the winter months, water should be applied within the dripline of a tree. The dripline circles the tree along the farthest reaches of the branches, typically.

3. Water deeply and slowly, applying water in a triangular pattern within the drip line.  You can use a soaker hose, by hand, or better a Ross or other brand of deep root feeder.

4.  Insert the deep root feeder needle 2-8 inches deep in the soil and water slowly.  As a general rule, apply 10 gallons of water for each diameter inch of the tree. For example, a two-inch diameter tree will need approximately 20 gallons per watering.

Do this and you help prevent drought stress. 

Like my grandfather used to say, “an ounce of prevention is worth a pound of cure.”

If you find your tree is not responding we do have a root stimulator that can help with root growth.


Concerned about your trees’ health and drought status?
Schedule your free onsite evaluation or winter watering, or call 303-806-TREE for more information now!


About the Author: David Merriman is an ISA arborist (#RM0786A), and owner of ArborScape, a Denver tree service. Read more articles at  www.arborscapeservices/blog.