Few do it on a regular basis. More people need to do it on warm days. Nope, I'm not talking about taking a
walk on a nice winter day. I'm referring to getting out your garden hoses or deep root soil needle and giving your trees and landscape a winter drink of water.
In the Denver area we're four inches of rainfall ahead of last year (as of late November 2014). It may seem like a skiff or inch or two of snow here and there is enough natural moisture. Is it? 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 the area is 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 and there isn't snow cover, 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 or 20 minutes or so. I may 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 areas. Insert the soil needle down no more than a foot (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 spot is saturated. Move it every five feet around the tree.
You can also use a soaker-hose, some call them weeper 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 into the air. Leave it in place until the screw driver goes down easily (check after each rotation), you may also need to soak and cycle using this type of hose 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, you may need to use some stakes to keep it in place.
Check your landscape soil every four to six weeks until your sprinkler system is turned on in the spring. Drag out the hoses if needed and water when conditions are right, you'll still have time to do a winter walk!
Read more - Fall and Winter Watering