by Leslie Lyles, M.S. |
Most of us like to ignore our landscapes as soon as the cold weather comes and the irrigation systems are shut down for the winter; however, during dry winters this can be a big mistake. In order for trees to survive the winter and be healthy, they need moisture. With that in mind, there is one landscape chore that needs to be done to ensure a healthy trees and shrubs—watering.
Many people believe that once their trees go dormant there is no need to water any longer. This cannot be further from the truth. Applying water to your trees during the dry winter months is one of the best ways to keep your landscape trees healthy. It is particularly important to provide winter water to young landscape trees (less than five years old) as these trees do not have as extensive a root system to rely on.
To understand why winter watering is so important one must understand the make-up of a tree’s root system. There are two basic types of roots on trees, structural roots and water absorbing roots. These roots have separate functions (just as your heart and lungs have separate functions). The structural roots’ primary function is for stability and anchorage of the tree, but they also serve as energy storage for the tree. These large diameter roots grow deep into the soil. The water absorbing roots are fine, small diameter roots that are found mostly in the top foot and a half of soil, where oxygen and moisture are plentiful. During dry winters, if the soil dries out too much, these fine roots desiccate (dry up) and die. In the spring, when it is time for the tree to come out of dormancy, the tree can not take up water and start producing leaves until it grows a new water absorbing root system. To do this, the tree uses energy from the structural roots, thus depleting its stored energy and ultimately stressing the tree.
So when and how should one water their trees? A good rule of thumb is to water your trees in the winter if there has been no significant precipitation (at least .5 inch) within a three to four week period. Most of a tree’s water absorbing root system is at the drip-line of the tree and beyond, so it is important to water out near the drip-line, not at the trunk (unless it is a newly planted tree whose roots have not left the root-ball). Make sure you apply enough water to soak at least eight inches deep into the soil. This can easily be done with a hose end sprinkler or a soaker hose.
If we do not receive sufficient natural precipitation in the winter months, watering your landscape trees is an important step in insuring their health.
References:
- Harris, Richard W. 1992. Arboriculture: Integrated management of landscape trees, shrubs, and vines. Second Edition. Prentice Hall.
- Pirone, P.P., Hartman, J.R. Sall, M.A. and. Pirone, T.P. 1988. Tree Maintenance. Sixth Edition. Oxford University Press, Inc.
For more info, contact Leslie Lyles at Stewardship Horticultural at (775) 849-1215.
