Near-total ponderosa mortality is projected along the Front Range within five years — a forecast already visible near Floyd Hill, where 20 acres of ponderosa are dead. The situation escalated enough that in December 2025, Governor Polis launched a Mountain Pine Beetle Task Force out of Evergreen to coordinate response efforts.
For homeowners, the threat is uncomfortably local. Stressed, dehydrated pines are beetle bait, and winter drought sets them up to fail by spring. Winter watering is one of the simplest, most cost-effective ways to help evergreens defend themselves — and it could mean the difference between a healthy pine and a dead one.
Key Takeaways
- Water trees in winter when temperatures are above 40°F, there’s no snow cover, and the ground isn’t frozen — typically 1-2 times per month from November through March.
- Apply 10 gallons of water per inch of trunk diameter, slowly at the drip line, to reach deep roots.
- Evergreens and newly planted trees need water during the winter most often because they lose moisture year-round and haven’t established deep root systems.
- Proper winter watering reduces drought stress, helping trees produce the resin that defends against mountain pine beetles now threatening Jefferson County.
Why Do Colorado Trees Need Water in Winter?
Colorado trees need water in winter because our climate creates a dangerous moisture deficit. Even in January, intense high-altitude sun warms bark and needles, causing trees to lose moisture through transpiration. But when the ground is frozen, roots can’t absorb water to replace what’s lost — a condition called winter desiccation.
Meanwhile, much of our winter precipitation never reaches tree roots. Snow often sublimates directly into our dry air or blows off slopes before it can melt and soak in. The result: trees enter spring already stressed and depleted, right when pests like pine beetles become active.
Why Is Winter 2025-2026 Especially Critical?
Trees heading into this winter are already running on empty. The year 2025 was ranked as the 10th-warmest and 51st-driest on record, according to the Colorado Climate Center.
Snowpack deficits meant trees entered winter with soil moisture already well below normal, which means root zones never fully recharged. For Jefferson County pines already under beetle pressure, this winter’s watering isn’t just maintenance — it’s triage.
Can Winter Watering Help Protect Trees from Pine Beetles?
Yes — winter watering helps protect trees from pine beetles by keeping them hydrated enough to produce resin, their primary defense against attacks.
Healthy trees defend against these boring insects by flooding their entry holes with sticky, aromatic resin. Mostly comprised of water-soluble compounds that trees manufacture and transport through their vascular system, resin can only be produced when soil moisture is sufficient.
When a beetle bores into the bark, a well-hydrated pine can generate enough resin pressure to physically push the invader back out, drowning it in sticky pitch before it can establish a gallery and lay eggs. A hydrated pine might fight off dozens of beetle attacks in a single season; a drought-stressed tree can’t mount even one effective defense.
Why Can’t Drought-Stressed Trees Defend Themselves?
Drought-stressed trees simply can’t produce enough resin to fight back. Without adequate soil moisture, they don’t have the resources to mount a pitch defense. That’s exactly why the current beetle outbreak is spreading so quickly — years of below-average precipitation have left Front Range pines unable to protect themselves.
Will Winter Watering Save an Already-Infested Tree?
Unfortunately, no; winter watering won’t save a tree that’s already infested. Once beetles have established galleries under the bark, the damage is done. However, consistent winter watering strengthens healthy trees against future attacks. For maximum protection, pair winter watering with preventive beetle spray treatments in spring (May through July).
How Do You Water Trees in Winter in Colorado?
In the foothills, winter drought is a bigger problem than the cold. Watering during this season isn’t complicated, but it does have rules. Water at the wrong time or in the wrong conditions and it can freeze at the surface, damage roots, or never reach the parts of the tree that need it. Done correctly, it prevents drought stress and helps evergreens enter spring strong enough to resist beetles and disease.
When to Water
The best time to water trees in winter is midday on a mild, dry day when the ground isn’t frozen; this gives water time to soak in before temperatures drop overnight. Aim for 1-2 watering sessions per month from November through March, conditions permitting.
Conditions You Need Before Watering
You need three conditions for effective winter watering:
- Air Temperature Above 40°F: Warmer temperatures allow water to soak into soil before freezing.
- No Snow Cover Over the Root Zone: If snow is present, your trees are already getting slow-release moisture as it melts — no supplemental watering needed.
- Unfrozen Ground: Poke the soil with a screwdriver to test — if you can’t push it in a few inches, the ground is too frozen to absorb water.
If there was decent and sufficient snowfall recently, however, you can skip watering. About 10-12 inches of snow equals roughly 1 inch of water, which is enough to sustain trees for 2-3 weeks.
How Much Water to Apply
Trees need about 10 gallons of water per inch of trunk diameter during each winter watering session. Measure your tree’s trunk about 6 inches above ground level, then multiply by 10. So, if your tree measures roughly 8 inches around, you’ll need to provide 80 gallons of water every time you go to give your tree a drink.
This calculation is approximate to what trees would receive from about a half-inch of rainfall over their root zone. Applied slowly at the drip line, the water soaks deep without running off.
Where to Apply Water
Water at the drip line – the outer edge of the canopy – not against the trunk. This outer perimeter is where most absorbing roots are located. Keep in mind that a tree’s root zone often extends as far as the tree is tall, sometimes farther.
How to Apply Water
The key to effective winter watering is slow application. Water delivered gradually over 30+ minutes soaks down to the 12-inch depth where deep roots can actually access it, rather than running off or pooling at the surface. Any of these methods work well:
- Soaker Hose or Tree Watering Bag: Provides consistent, slow delivery across the root zone.
- Regular Hose on Trickle: Let it run slowly for 30+ minutes, moving it around the drip line.
- Buckets or Watering Cans: Adequate for smaller trees and shrubs.
PRO TIP: Mulch extends your watering efforts. Apply 2-4 inches of organic mulch from the trunk to the drip line (but keep it several inches away from the bark). Mulch slows evaporation, stabilizes soil temperature, and helps every gallon you apply last longer. Just don’t build a mulch volcano!
Which Trees in Colorado Need Water During Winter the Most?
Evergreens, newly planted trees, and trees in high-stress locations need winter water most. If you can’t water every tree on your property, prioritize these.
Why Are Pines and Evergreens the Top Priority?
Pines and evergreens are the top priority because they’re the primary targets for bark beetles — and right now, with the active outbreak in Jefferson County, a stressed ponderosa is both a beetle magnet and a potential fire hazard.
Why Do Newly Planted Trees Need Extra Winter Water?
Newly planted trees need extra water because they haven’t developed the deep root systems required to access moisture during dry periods. Trees planted within the last 2-3 years depend on surface moisture and are far more vulnerable to winter drought than established trees.
Why Do Evergreens Need More Water During Winter Than Deciduous Trees?
Evergreens struggle more throughout winter because they continue losing moisture through their needles year-round, even when deciduous trees are fully dormant. This process — called transpiration — doesn’t stop just because temperatures drop. When soil moisture is low, evergreens can’t replenish what they lose, leaving them stressed and vulnerable to spring pests.
Which Landscape Locations Create the Most Tree Watering Stress?
South-facing slopes, windy exposures, and areas near pavement create the most stress for trees:
- South or West Exposures: More sun means more moisture loss.
- Windy Locations: Accelerates evaporation from soil and needles
- Near Pavement or Foundations: Reflected heat dries soil faster; root zones may be limited.
When Should You Call an Arborist for Winter Tree Care?
Call an arborist if your trees show stress signs that watering alone won’t fix — or if you want professional help keeping high-value trees healthy through the winter.
These signs indicate you need professional help rather than just more water:
- Pitch Tubes on Pine Bark: Small resin globs indicating possible active beetle infestation.
- Significant Needle Drop or Browning: More than normal seasonal shedding suggests stress or disease.
- No Improvement After Consistent Watering: Something else is wrong and needs diagnosis.
- Large, Mature Pines to Protect: Preventive care costs far less than removal.
What Is LAM’s Winter Watering Program?
LAM’s Winter Watering Program is a professional deep-root watering service that delivers water directly to the root zone where trees can actually use it.
Here’s how it works: We inject water and soil conditioner directly into the soil at 6 to 12 inches deep — right where absorbing roots are located. Because the water goes straight to the root zone, nothing is lost to evaporation or surface runoff. Each treatment delivers the equivalent of about a half-inch of rainfall exactly where your trees need it.
During dry winter stretches, our crews return every 10 to 14 days to monitor and maintain consistent soil moisture. We also offer an optional soil conditioner that helps the ground hold moisture longer — especially helpful during drought years when every drop counts.
Frequently Asked Questions About Winter Tree Watering
Does winter watering attract rodents or pests?
No — winter watering doesn’t create conditions that attract pests. Healthy, well-watered trees are actually better able to resist pest damage. Rodents seek shelter and food sources, not soil moisture. If you’re concerned about rodent damage to young trees, wrap trunks with tree wrap or hardware cloth.
Will winter watering help my aspens?
Yes — aspens benefit from winter watering, especially young trees and those showing stress. However, aspens face multiple challenges in Jefferson County, including aphids, fungal diseases, and cytospora canker, so watering helps but may not address underlying issues. A professional assessment can identify the root cause if your aspens show significant decline.
How do I know if my soil drains well enough for winter watering?
Check the area an hour after watering. If water is still pooling on the surface, your soil has poor drainage and additional water risks root rot. Most foothill soils drain well, but heavy clay or compacted soils near construction may need amendments first.
Is it worth watering mature trees that have been here for decades?
Absolutely — especially during a drought. Mature trees have extensive root systems but can still become stressed during extended dry periods. A stressed mature tree is more vulnerable to pine beetles and losing a 50-year-old ponderosa costs far more than the time spent watering it.
How LAM Tree Protects Your Property Through Winter
The ponderosas dying at Floyd Hill right now weren’t killed by beetles alone — they were killed by drought stress that left them unable to fight back. Your trees don’t have to be next. Winter watering is one of the few things you can do right now, before beetle season arrives, to give your pines a fighting chance.
Need help? LAM Tree’s Winter Watering Program delivers professional deep-root watering with soil conditioner throughout the dry season. And if you’re already seeing signs of stress or beetle activity, schedule a consultation with our ISA Certified Arborists before spring.
