SuperTrees Blog

Winter Trees: Why Winter Watering is Essential

Written by SuperTrees Team | Dec 11, 2025 4:45:00 PM


When we look at the winter landscape, we see nature at rest. Winter trees may be resting, conserving strength and energy for spring; those of us who tend to them, whether at nurseries, city and urban foresters, landscapers, or even homeowners, need to be paying close attention.

There’s quite a bit we can be doing over the winter, from pruning to watering, to ensure we get the most out of our trees in the spring and ensure they grow healthy and strong.

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Why Winter Trees Still Need Water

Even though leaves fall and growth slows, winter is far from a time to “forget” your trees. While the tree above ground appears to be at rest, the root system stays alive through the dormant season and continues to lose moisture into the soil.

In dry winters (or stretches without snow), roots can dry out, causing stress, root dieback, or even death. This is especially true for newly planted trees and evergreens.

As a wholesale nursery, we think of trees as an investment, which means caring for them so they’ll live out their whole lifecycle. Protecting the root system year-round is a key component of tree health. 

Here are some practical truths behind that long view:

  • Roots grow and need moisture in winter. Many species extend or repair roots in the cooler months, so adequate soil moisture supports strong spring growth and long-term survivability.
  • Evergreens are at higher risk. Because needles remain through winter, evergreens can lose water to wind and sun and may need supplemental watering more often than leafless deciduous trees.
  • Lack of snow or long dry spells are the danger times. Suppose your region (we’re looking at Colorado/Utah and the PNW in particular) gets long stretches without measurable precipitation or insulating snow cover. In that case, roots can dry, and soils can hold less available moisture.

Whether you’re tending newly planted or young trees, or simply live in an area known for its dry conditions, dormant season doesn’t mean the trees can hold their own. 

The Consequences of Skipping Winter Watering

When you forget to water a plant, it may wilt or show other visible signs of struggling. For trees, skipping supplemental watering when it’s needed can lead to a cascade of long-term problems, many of which only become obvious in spring or even the following year.

And, in some cases, the wholly avoidable consequences are serious.

1. Winter Desiccation and Evergreen Damage

One of the biggest issues we see is winter dry-out, especially in evergreens. Even in cold weather, evergreens lose a bit of moisture through their needles on sunny or windy days. If the soil is dry or frozen and the roots can’t pull in enough water to replace what’s lost, the needles dry up, turn brown, and die back.

If the soil is dry or frozen, roots can’t replenish that water fast enough; the result? Needles dry out, brown, and eventually die back, with damage often worse on the side facing prevailing winds or afternoon sun. And, in severe cases, entire branches or even the whole tree can suffer.  

2. Root System Injury and Winter Mortality

Dry soil in the root zone during winter can be deceptively dangerous. Long dry spells (especially before the soil freezes) can injure or kill parts of the root system.

When root systems are compromised, trees may appear “fine” in spring as they can use stored energy reserves, but they’re actually weak. Over time, they have poor growth, branch dieback, or some even die as the tree struggles to recover.

In young or newly planted trees, the risk is even higher. Because they have fewer established roots, they’re more vulnerable to moisture stress during winter.

Similarly, lowered root reserves (e.g., carbohydrate or sugar reserves) are particularly problematic; research shows that drought-stressed seedlings may not recover in spring and may instead die during or after winter because their roots have lost vitality.

Additionally, freeze–thaw cycles, which are becoming more frequent with climate change, can physically damage fine roots. In one study of silver birch, freezing reduced root longevity and increased fine-root mortality.

3. Increased Vulnerability to Pests, Diseases, and Secondary Stress

Trees weakened by winter water stress don’t just struggle with water; they're also more susceptible to other threats. Drought-stressed trees (including those lacking winter water) have reduced defense mechanisms, making them more vulnerable to insect infestations or disease.

4. Frost Damage, Sunscald, and Bark Injury

And, it’s not just structural weakness or pests to worry about. Without adequate hydration, trees are more vulnerable to specific cold-weather injuries. For example, low soil moisture can worsen the effects of temperature swings, contributing to sunscald (also known as “southwest winter injury”), especially on thin-barked trees.

When bark is weakened or damaged in this way, it can crack, die back, or become infected. Winter wind, snow, ice, and frost can also damage branches, and trees with low moisture don’t have the strength to withstand those stressors or recover from the damage come spring.

Practical Tips for Watering Winter Trees

Now that we’ve established that winter trees need watering, it’s important to discuss how and when to water. It’s not quite the same as watering in summer. Fall tree care, including mulching and soil monitoring, can help make winter care easier.

When it comes to established trees, not the brand-new ones (we’ll get to that), these are the strategies that help protect mature roots and keep trees resilient through dry, cold months.

  1. Time Your Winter Watering

    • Only water when the soil can absorb moisture. Wait until air and soil temperatures are above about 40°F — frozen or snow-covered ground won’t take water and can cause runoff or ice buildup.
    • Water in late morning or midday, when the ground has warmed slightly, and the water has time to soak in before evening temperatures drop.
    • Once the soil freezes solid, pause winter watering. Water can’t penetrate, and you risk creating surface ice.
  2. Water Deep, Not Shallow

    • Aim to moisten the soil 8–12 inches deep beneath the canopy; that’s where most fine roots live.
    • Use slow methods like a soaker hose, drip line, or hose trickle to avoid runoff and help moisture move deeper into the soil.
    • For established or larger trees, water across the entire root zone, not just near the trunk. Roots often extend as far as (or beyond) the canopy.

  3. How Much to Water

    • A simple rule of thumb: 10 gallons of water per inch of trunk diameter per watering for established trees. A tree inventory ensures you’ve got this data on hand.
    • For larger trees, water in several spots along the dripline to ensure even coverage and minimize runoff.
    • Deep but infrequent watering encourages strong, deep roots. Shallow or frequent watering weakens root structure.

  4. Monitor Soil Moisture

    • Check moisture 6–9 inches below the surface using a screwdriver, trowel, or your fingers. If the soil is still damp, you can skip watering.
    • In long dry spells, check more often. Wind, winter sun, and exposed sites can quickly dry soil.
    • Be cautious in clay or loam soils; too much water can displace air pockets and suffocate roots.

  5. Mulch Wisely

    • Keep a 2–4 inch layer of mulch out to the dripline, but avoid piling it against the trunk. Mulch helps retain moisture and buffer temperature swings.
    • Top off mulch if it settles during winter to maintain a consistent layer.

  6. Be Strategic About Stress Factors

    • Trees in windy, exposed, or thin-soil locations dry out faster and may need extra watering.
    • Avoid fertilizing in late fall or winter. Stressed roots can’t support new growth.
    • Watch for soil compaction or nearby landscaping work; compacted soil holds less water and limits root recovery.

  7. Be Consistent but Flexible

    • Create a schedule that fits your climate. In dry winters, you may water every 3–4 weeks; in wetter or snowy winters, you may not need to water at all.
    • Use weather forecasts to plan: water before warm, dry spells and pause during freezes.
    • Reassess annually. Winter moisture patterns can change year to year.

  8. Prevent Secondary Stress

    • Ensure proper drainage to avoid pooling water or runoff. Adjust watering methods as needed.
    • Remove grass or weeds under the tree; they compete for winter moisture.
    • Use protective measures (like trunk wraps) for thin-barked trees prone to sunscald or winter bark injury.

Special Considerations for Newly Planted Winter Trees

Fall is one of the best times for tree planting, but that means newly planted trees need more hands-on care come winter. While many established landscaping trees can cruise through winter with occasional deep watering, young root systems haven’t spread far yet, so they dry out faster and depend heavily on consistent moisture during the dormant season. The first two winters can make or break a young tree’s long-term health.

Here’s what to keep in mind:

  • Water more frequently during dry spells, generally every 2–3 weeks when temperatures allow.

  • Use deeper soaks, aiming for 5–10 gallons per inch of trunk diameter.

  • Focus on the root ball and just beyond, as this is where most new roots are developing.

  • Protect trunks with wraps or guards if your region has strong winter sun or freeze-thaw swings.

  • Monitor stakes and ties, as winter winds can loosen them, and a young tree that wobbles a lot in the wind will struggle to root in.

From our perspective, as a nursery that cares about long-term tree health, these watering practices are not just about helping trees survive; they’re about helping them thrive.

Ensuring established trees don’t enter winter already stressed sets them up to bounce back stronger in spring, resist pests, and grow steadily year after year. Proper winter watering is a relatively small effort that pays off in root resilience, vigor, and durability.

If one thing is clear, it’s that the roots are doing the heavy lifting year-round, and that’s why we focus on growing trees with strong, healthy root balls, made possible by air-pruning technology. From seed to service and support, we’re here to help you ensure healthy trees year-round, and we hope you’ll reach out!