Supplemental irrigation for plant material during a dry winter in the Great Basin desert of Northern Nevada is often neglected, and is an important factor influencing plant health. Northern Nevada winters are unpredictable with temperatures ranging between 60 degree days and sub-zero nights. Northern Nevada receives the majority of it’s average annual precipitation of only 7.0 inches in the winter, but sometimes there are many weeks between measureable precipitation. Landscape plants can suffer from drought in the winter even though the plants are mostly dormant.
During the growing season it is obvious landscape plants need irrigation to survive; because without irrigation, plants quickly show signs of drought stress. During the winter months, plants are dormant and show no visible signs of activity, but they are very much alive. Wintertime moisture keeps plant roots hydrated, prevents the soil from shrinking and cracking causing root damage, and helps prepare them for springtime’s return to the growing season. All evergreens, especially broad-leaf evergreens such as Rhododendrons continue to transpire moisture through the leaves. If the moisture level drops in the roots, the leaves can dehydrate and fall off. Drought damage to a coniferous evergreen is insidious because it can take months to show.
In the winter, prevent plant dehydration during periods of drought by pressurizing your irrigation system on a warm sunny day and run through all the valves. Remember to water lawn areas as well. After watering, shut-down and drain your irrigation system to prevent freeze damage. If you do not want to turn on your sprinklers, you can always hook up the hose and water by hand. A good rule of thumb is to water shrubs for five seconds, and 20 seconds to a minute for trees. This will take care of the water needs of the plant material for an interim winter watering session.
When periods of four to six weeks go by without sufficient moisture, we recommend watering your yard. If the top one to two inches of soils is dry, it is a good time to water. Do not worry about watering if there is still snow on the ground. It is acting as an insulator and moisture blanket and there is no need to water.
