It’s a question I get asked all the time at the nursery: Do you need to water your garden in winter?
Yes, you do. While your garden has gone dormant, your plants still need water to fuel basic metabolic functions. Unless we have an unusual amount of winter precipitation, you’ll need to water your trees, shrubs and perennials.
THIS YEAR’S RAIN AN EXCEPTION AFTER VERY DRY YEARS
Arizona’s historic rainfall this monsoon season made the news several times this summer. (Who can forget the videos of the car floating down streets due to flash floods?) But that came after two back-to-back “nonsoons” in 2019 and 2020. Technically, our state is still in a drought.
Meanwhile, the National Oceanic and Atmospheric Administration predicts a La Niña winter. That means drier conditions and less snow.
Add to that the cold and wind of winter in Arizona’s high country and you have a perfect storm of conditions leading to very dry soil and a lot of drought stress for plants.
HOW OFTEN (AND HOW MUCH) DO I NEED TO WATER?
You should plan on watering once or twice a month during the winter. Because that watering schedule is so infrequent, you might want to put it in your day planner. And, of course, you’ll be watering by hand since you should have winterized any drip irrigation system you have.
Another question we get a lot is how much water is enough during the winter. It depends on the size of the tree, shrub or perennial plant and whether it is new or well-established.
As a general rule, you’ll need about 10 gallons of water for each diameter inch of the tree. For example, a two-inch diameter tree needs 20 gallons per watering. The trick is to water slowly; you can’t just dump 10 or 20 gallons of water all at once, as it will run off instead of soaking down to the roots.
Newly planted shrubs require about twice as much water as an established shrub needs. You should be looking at 5 gallons each time you water a new shrub and 2.5 gallons for shrubs planted at least a year ago. Make sure they are surrounded by mulch to help them retain the water.
Perennials vary, but know that those planted late in fall will not have had as much time to establish their roots as the ones you put into the ground this past spring. Winter watering is highly advisable for late-planted perennials and ones located in windy or southwest exposures.
WHAT ABOUT FREEZES?
It’s a good idea to make sure that temperatures are going to hit about 40 degrees on the days you are watering, and you’ll want to water by midday to make sure it’s been absorbed before any nighttime freezes.
You’ll also want to try to water when it isn’t windy out. A drying wind could wind up carrying off the moisture you are trying to get to the roots of your plants.
By watering your garden in winter, you are increasing the chances that your garden, trees, shrubs and perennials will be lovely and lush next spring.
Happy gardening (and watering!)