Repeating this timely blog from three years ago - with a few revisions.
Few do it on a regular basis. More people need to do it on warm days. I'm not talking about taking a walk on a pleasant sixty-degree winter day. I'm referring to giving your trees and landscape a much needed winter drink of water.
In the Denver area we've had a trace of precipitation the past several weeks. We've broken three temperature records in the past six days. Last Friday we hit 80 degrees! You might be thinking because its winter there's no need to react to warm temperatures or the lack of moisture...right? Please don't assume or guess that your landscape isn't dry without physically checking. Grab your longest screw driver and poke it down in to the ground through the mulch, the grass and especially on sunny south, west or southwest facing areas. Check anywhere the soil isn't frozen. If it doesn't go down easily, then you're dry, if you need to use most of your weight to get it down, then you're parched.
Winter watering is one of the best things you can do for your landscape. On-going or prolonged dry plant roots in the winter can lead to root damage, death or reduced plant vigor.
During the middle part of the day when temperatures are over forty degrees, set up your sprinkler and move it around the drip line (outer branch tips) of trees or close to the trunk if the tree is new or young.
I make it super easy on myself and set the timer and move the sprinkler every 15 to 20 minutes or so. Circle back and repeat the same spots (soak and cycle) if the area is severely dry. Soak and cycle helps the water soak down avoiding water waste and run-off.
If you want to use the deep root soil needle then plan on an hour or more of hands-on time for large trees and other areas. Insert the soil needle down no more than a foot or eight inches (that's where most of the roots are located) and let it run five or so minutes in each spot, you'll know when the area is saturated. Move it every five to eight feet around the tree. Don't forget the shrubs too.
You can also use a soaker-hose, some call them weeping hoses and extend it around the tree drip line (or closer for new trees). Make sure the water pressure is low so it soaks downward and not up and misting the air. Leave it in place until the screw driver goes down easily (check after thirty minutes), you may need to soak and cycle using the soaker if the area is super dry. Keep in mind that soaker-hoses aren't as easy to place around the tree when the hose is cold from being in your shed or garage, use some stakes to keep it in place.
Check your landscape every four to six weeks if there's a dry weather pattern.
If you are growing garlic that was planted last fall they probably need a drink too, check them!
After watering you still have time for that winter walk.
Read more from CSU Extension - Fall and Winter Watering