Lack of adequate soil moisture is often a major cause of winter damage. Dry soil coupled with strong winter winds can cause havoc on a plant. All plants, especially narrowleaf and broadleaf evergreens, use water during winter. When little or no soil moisture is present, plants can become desiccated and it is more likely root damage will also occur.
When dry cold fronts are predicted, water the landscape at least 24 hours in advance of the front. Apply about 1⁄2 inch of water at the time of watering. A sunny day on moist soil helps warm the soil and root area thus reducing the amount of time the roots will be exposed to cold temperatures.
Moisture must be available below the frost line or frozen soil. When the soil freezes, if moisture is not present in soil pore spaces, moisture is pulled from plant roots to form the ice crystals resulting in desiccated roots, thus what some would refer to as “winter kill.”
Of course some common sense needs to be practiced at this time of year: do not allow the sprinklers to come on during a hard freeze. Ice forming on some plants could result in some serious damage and you could create a hazardous situation for you, pedestrians or even passing vehicles.
Too much water can also result in problems during the winter. Cold wet soils can lead to rotting roots. Soils with more than ample moisture may also encourage winter weeds to germinate and flourish. Water only every two to three weeks and apply only enough water to moisten the top six or so inches of soil.
Do not forget plants growing in above-ground planters protected from rain. They need watering even in a wet season. Also, remember to water plants that are located under the eaves of a building or home since they often receive little natural precipitation.