It’s important to water trees in the winter
I’m pretty sure the lady who drove past my house as I was dragging the hose across the lawn thought I was crazy. But after the last bit of snow melted in the front yard, and I could go outside without a parka, it was time to water my poor trees.
Although we’ve had a bitterly cold winter here in the Grand Valley, and a crust of snow that hung around for quite a while, we haven’t had the benefit of much precipitation.
Cold winters with little precipitation can damage or kill root hairs, which are very tiny and delicate but extremely important for your trees and shrubs, since they allow the plants to utilize water and minerals. If root hairs die during a dry winter, this affects the tree in the springtime and could make the tree more susceptible to disease later on, because it cannot effectively use the water and minerals it needs to be healthy.
I’m especially concerned about a weeping white birch tree we have in the front yard, which isn’t a tree I would have chosen to plant here in our climate, but it came with the house.
It’s a shallow-rooted tree, making it more susceptible to hot, dry conditions. To make matters worse, it’s located on the southwest side of our house, which receives the most sun. In past years, when I’ve neglected to water this tree during a dry winter, I’ve noticed that the leaves have a distinctive brown scorch around the edges, which lasts until the next fall.
Colorado State University Extension recommends watering once or twice a month if there has been little precipitation, there’s no snow cover and temperatures warm to above 40 degrees during the daytime.
This goes for newly planted trees, shrubs and perennials as well. The general recommendation is to water newly planted shrubs 5 gallons, twice a month from October through March. However, even small established shrubs can benefit from 5 gallons once a month. Large established shrubs, at least 6 feet tall, should receive about 18 gallons per month, according to CSU Extension.
Lawns can also benefit from winter watering, but it’s just not practical for most of us to fire up our sprinklers (if you had irrigation water) and winterize the system each time.
With trees, you should plan on watering at least once a month (twice if it has been really dry) and you need to estimate how much water to apply. CSU Extension recommends applying 10 gallons of water for each inch in diameter of that tree’s trunk. So, if I have a tree with a 10-inch diameter trunk, I need to be applying 100 gallons of water within the root zone.
How do I know how large my tree trunk is? I measure it. How do I know how many gallons of water are flowing out of the hose? I measure that, too. I take a bucket that has one gallon clearly marked, turn the hose on to what I consider a fast trickle (you don’t want the water pressure to be too high, or it won’t absorb into the soil), and time low long it takes for the water to measure one gallon. Then I take that time and figure out how long the hose should run at that rate for that particular tree.
I’ve also heard of people using 5-gallon buckets with holes drilled in the bottoms. You can fill up the buckets and let them slowly drain into the root zones, and that takes the guess work out of determining how fast your hose is running. This could work really well for smaller trees and shrubs.
Winter tree watering is an all-afternoon project at our house, because we have really large trees. I drag out the hose, turn it on to what I would consider a fast trickle, and place the hose at the edge of the root drip line (the place on the ground directly under the far reaches of the branches). For our larger trees, that means I’m at least 10 feet from the trunk, and I’m using the upper reaches of the branches to estimate how far out the roots reach underground.
I’ve seen people water trees directly next to the trunk, which is not effective. The root hairs you’re trying to hydrate are at the ends of the roots, not next to the trunk.
Because I’m terrible at watching the clock, I set a timer so I don’t forget to go outside and drag the hose around the circumference of the tree line. This can take hours for larger trees. I try to finish watering before late afternoon, because I don’t want the water to freeze into a sheet of ice, which can also damage roots and grass.
Of course, don’t forget to disconnect the hose from your faucet after watering, and drain the water from the hose so it won’t freeze and expand.
For information on winter watering, check out the CSU Extension at http://www.ext.colostate.edu or contact the Mesa County Master Gardener desk at 244-1836.