Winter Watering Tips
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The following are common questions received by Johnson County Extension about applying water during winter so as not to harm plants or equipment.
Should I water during a winter drought?
During periods of winter drought, people become rightfully concerned about their landscape plants and home foundations. During a winter drought, horticulturists encourage people to water trees, lawns and shrubs and to protect their foundations by using sprinklers and soaking hoses nearby.
At what temperatures should water be applied to plants? Will frozen water harm the plants?
Water can be applied to landscape plants any time the temperature is above freezing and the soil is not frozen so that it can soak into the ground. Once the water is applied, the temperatures can drop below freezing and there will be no harm to the plants. Although most outside faucets have a drain to prevent freezing, for safety reasons, it is best to remove the hose from the faucet and completely drain the hose and sprinkler once the water is applied. A hose attachment does not allow for proper drainage.
What about draining automatic sprinklers?
Underground irrigation systems have several methods of draining for the winter months. It is best to check with your system contractor to determine if it should be used during the winter months. Keep in mind a day or two of freezing temperatures should not harm an underground system, as the soil is warm and insulates the pipes. Extended cold, winter weather will damage an underground system if not properly prepared for winter.
How much should I water?
As a general rule of thumb, soak the soil to at least a depth of 6 to 8 inches. This holds true for the lawn, flowers and some trees and shrubs. This depth provides moisture to the crowns and a vast majority of the feeder roots. Trees should be soaked more deeply.
How long should the water be applied in order to meet these criteria? There is not an easy answer. How long to let the water run depends on the system applying it and the water pressure. The best way to measure your water output is with the use of a rain gauge. For example, to apply an inch of water using an impact sprinkler in a full circular pattern often takes four hours or more.
How often should I water?
Here, again, it depends on the type of plants, soil and weather conditions. However, a soaking every two to four weeks is normally sufficient. When in doubt, probe the soil using a screw driver or metal rod. When the soil is dry, reapply water according to the above recommendations.
Which plants need watering the most? 
Plants most likely to suffer from winter moisture shortage are fall-established lawns, young trees and shrubs which are five years of age or less, and especially evergreens, which are at the greatest risk during a winter drought.
Have questions?
The Garden Hotline is staffed by trained EMG volunteers and Extension staff who will assist you with questions.
Phone: (913) 715-7050
Email: garden.help@jocogov.org