You Still Need to Water in Winter

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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.

And while it might seem silly to mention this after the massive snowfall we’ve seen recently in Flagstaff, it’s meant to be a reminder to keep caring for your trees and plants this winter after the snow melts. As a rule of thumb, about 10 inches of snow equals about 1 inch of water, so even this historic snowfall won’t provide all the water your trees and perennials need for the season.


Arizona’s past two monsoon seasons and this month’s snowfall were exceptional, and not the rule for northern Arizona.

In general, our area tends to be arid, a trend that has worsened over the years because of climate change. 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 even in years with snow and rain.


You should plan on watering once or twice a month during the winter when there isn’t snow cover and temperatures are above 40 degrees. 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 often get 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 did not have as much time to establish their roots as the ones you put into the ground this last spring. Winter watering is highly advisable for late-planted perennials and ones located in windy or southwest exposures.


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 – even a winter like this one with lots of snow – you are increasing the chances that your garden, trees, shrubs and perennials will be lovely and lush next spring.

Happy gardening (and watering!)