Trees and Shrubs Winter Watering
Boulder Colorado landscapes – Plant of the Month Series
Winter watering of evergreen trees and shrubs is as important to maintaining a healthy landscape as watering in the summer. It is especially true with evergreens, because, unlike deciduous plants that lose their leaves in the winter, evergreens will continue to transpire water and nutrients, even in the coldest of temperatures. Although they use less water than during their flush growing season in the spring, they still require more water than deciduous plant material. The general rule of thumb to use is as follows: If there has not been snow on the ground under or around a particular tree or shrub on your property for three weeks, it needs water. It is phrased this way because a tree on a soil berm on the southwest corner of a property exposed to sunlight will be snow free with non-frozen soil far sooner than a shaded area on the north side of a fence or home. Perennial flowers and turf grass are generally OK without additional winter watering except in the driest of winters.
Trees and shrubs, especially coniferous plants like Pine, Spruce or Fir or broad leaf evergreen shrubs like Holly, Euonymus, or Boxwood are especially prone to drying out in the harsh winter winds we have in our Boulder Colorado landscapes. The rate at which to water varies, but in general, for deciduous trees, water 10 gallons for every 1” of trunk diameter throughout the root zone, or slightly more. For shrubs, the amount of water varies greatly due to size, but, on average, for every 1’ of height, water with 3 gallons of water. For evergreen trees, water 1 gallon or more for every 1’ of height. Do not water when the ground is frozen. And, only water then the temperature is above 45 degrees. Well established trees need little additional water except in the driest of winters. However, it takes a long time and a lot of water to soak the roots of a 60 foot Oak. These suggestions are mostly for younger, less mature plant material. Your experience with your own property will dictate your winter watering schedule.
Each winter presents a different scenario for winter watering. However, if you have been enjoying warm weather in January and February, and not shoveling snow every other week, then you should consider watering plants on your property. Remember to drain the hoses thoroughly, or you will be fighting ice in the hose the next time you try to water!