Why Winter Watering Is Critical for Tree Health

As a Colorado arborist, one of the most important—and most overlooked—pieces of advice I give homeowners is this:
Don’t forget to water your trees in winter.

Colorado’s cold season may look quiet and dormant, but below the surface, your trees are still very much alive. Ensuring they have enough moisture during this period can mean the difference between a healthy, resilient tree and one that struggles all year long.

Colorado Winters: Beautiful, Dry, and Hard on Trees

Colorado’s winter is not like winter in other states. Here’s why our trees are especially vulnerable:

1. Extremely Dry Air

We have one of the lowest humidity levels in the country. Even in winter, when trees aren’t actively growing, they continue to lose moisture through their needles and bark.

2. Very Little Natural Moisture

Snowfall is common, but snow provides surprisingly little usable water. Much of it sublimates—turns from solid to vapor—without ever melting into the soil.

3. Freeze–Thaw Cycles

Our warm winter days followed by freezing nights cause:

• Soil to dry out
• Roots to become exposed to cold, dry pockets
• Moisture loss to accelerate

4. Evergreen Stress

Evergreens (spruce, pine, fir, and juniper) don’t go fully dormant. They keep photosynthesizing and losing moisture through their needles. Without water, they can dehydrate—even under snow.

What Happens to Trees Without Winter Watering

When trees don’t get enough winter moisture, several problems follow:

1. Winter Desiccation

This is one of the biggest killers of Colorado trees. It happens when a tree loses more moisture than its roots can replace. Needles turn brown, branch tips die back, and entire sections of the tree can fail.

2. Root Damage

Dry roots become brittle and are more vulnerable to freezing injury. Damaged roots mean reduced nutrient uptake in spring, leading to weak growth.

3. Increased Pest & Disease Vulnerability

Stressed trees are magnets for:

• Ips beetles
• Bark beetles
• Cytospora
• Borer insects

Healthy, hydrated trees are far more resistant.

4. Slow Spring Recovery

Trees that don’t receive winter water leaf out later, grow less, and show signs of canopy thinning over time. Chronic winter drought can shorten a tree’s lifespan.

What Trees Need Winter Watering?

In Colorado, almost all landscape trees benefit, but it’s especially important for:

• Newly planted trees (1–5 years in the ground)
• Evergreens
• Colorado blue spruce
• Maple varieties
• Aspen
• Ornamental trees
• Shrubs, especially broadleaf evergreens
• Trees in rock beds or xeriscapes
• Trees near south- or west-facing walls

Even mature native trees benefit during prolonged dry spells.

When and How Often Should You Water?

A good rule for Colorado homeowners:

Water once every 3–4 weeks during dry periods when:

• There is little to no snow cover, and
• Temperatures reach above 40°F (4°C) for several hours

Winter watering should continue from October through April during dry stretches.

How Much to Water

For established trees:

• Apply water to the entire area under the canopy and a few feet beyond
• Aim for 10–20 gallons per inch of trunk diameter over the course of your watering session

For newly planted trees:

• Water more frequently—every 2–3 weeks
• Apply 5–10 gallons each time, depending on size

How to Water Correctly

• Use a hose on a slow trickle
• Avoid watering right at the trunk
• Focus on the “dripline”—the area beneath the outer branches
• Allow water to soak deeply into the soil (12–18 inches)

Visible Signs Your Trees May Be Suffering Winter Drought

Watch for:

• Browning or purpling needles
• Dieback at branch tips
• Thinning on one side of an evergreen
• Entire sections failing to flush in spring
• Leaves that emerge small, pale, or sparse

These are often moisture-related stress symptoms.

From Your Arborist: The Bottom Line

Colorado’s climate is tough on trees—especially in winter. While it’s easy to assume that dormant trees don’t need supplemental water, the opposite is true. Winter watering is one of the simplest, most cost-effective ways to preserve the health, beauty, and longevity of your trees.

A few minutes with a garden hose during dry winter months can prevent years of stress and thousands of dollars in potential tree loss.