Why water in the winter? Aren’t plants dormant?
Winters in Northern Colorado are often dry and this is the new normal. Plants, young trees, shrubs, and lawns can become damaged without sufficient moisture. The driest months tend to be October through March every year since we do not have adequate snowfall during these months.
According to the CSU extension, a good rule of thumb is if 4 weeks have elapsed without any snow or moisture, then water when temps are above freezing and closer to midday so the water can soak in before the temperatures start to drop. This is important for young trees and shrubs or newly established lawns (seeded or sod) because they won’t have established root systems to sustain them through the dry months. Also, shrubs and lawns with south and west exposure will be drier since the sun here in Colorado can be intense and increase dryness.
Plants and trees won’t die immediately without water but it can weaken them. The CSU Extension notes, trees, shrubs and turf might initially return in the spring, but often are more susceptible to diseases and lawn damaging insects and can die off in the hot summer months. We have observed large scale mite damage in the past few years due to lack of moisture and warmer winters which is a perfect breeding ground for these very small insects.
A good guide is 10 gallons of water for each diameter inch of the tree. So a 3-inch diameter tree would receive 30 gallons of water. Turn on your hose super slow and let it trickle so it soaks in deeply and reduces runoff. Water your grass for at least 20 minutes by a hose end sprinkler since irrigation systems are winterized.