Quick Answer
Don't automatically stop watering in October. According to CSU Extension, Colorado plants (including dormant trees and shrubs) may need supplemental water during prolonged dry periods throughout fall and winter. Water once or twice monthly when air and soil temperatures are above 40°F, the ground is not frozen, and there has been no meaningful snow cover. The key is monitoring conditions rather than following a fixed calendar date.
What This Guide Covers
- Why Colorado winters can damage trees even when they look dormant
- The conditions that determine when to water
- How often and how much to water in fall and winter
- Which plants are most at risk
- Practical steps for winter watering
- When professional help may be appropriate
Why Colorado Winters Can Dry Out Trees
Colorado's winters are often sunny and dry, with low humidity and periods of little or no precipitation. Even though trees are dormant and not actively growing, their roots continue to function and need some moisture to survive. When soil dries out completely during winter, roots can desiccate (a condition called winter desiccation or winter burn), which weakens or kills the plant.
Evergreens are particularly vulnerable because their needles continue to lose moisture through transpiration even in winter, but deciduous trees and shrubs can also suffer root damage during extended dry periods.
The Four Conditions for Winter Watering
Before watering in fall or winter, confirm that air and soil temperatures are above 40°F, the ground is unfrozen, and little or no snow cover is present:
Air temperature above 40°F
On colder days, water may freeze or fail to soak in before overnight temperatures drop.
Soil temperature above 40°F
Frozen soil cannot absorb water effectively. Check soil temperature a few inches down.
Ground is not frozen
If the surface is frozen solid, wait for a warmer day when the top few inches have thawed.
No meaningful snow cover
After precipitation or snowfall, check actual soil moisture. Existing moisture may reduce or eliminate the need for supplemental watering.
How Often and How Much
CSU Extension recommends watering once or twice monthly during dry fall and winter periods when the conditions above are met. Apply water slowly across the root zone, aiming to wet the soil to about 12 inches. Midday watering is preferable in winter so water has time to soak in before temperatures drop overnight.
Winter Watering Checklist
- Monitor fall and winter precipitation. Don't assume snow is enough
- Check air and soil temperature before watering (both should be above 40°F)
- Water midday so it soaks in before overnight freezing
- Apply water slowly across the full root zone, not just at the trunk
- Water once or twice monthly during dry periods
- Pay extra attention to evergreens and newly planted trees
- Disconnect and drain hoses after each use to prevent freezing
- Resume spring irrigation according to current soil moisture, weather, plant needs, and safe system startup timing
When Professional Help May Be Appropriate
If you notice needle browning on evergreens in late winter or early spring, or leaf scorch and dieback on deciduous trees after a dry winter, a professional can assess whether winter desiccation is the cause and recommend a recovery plan. Irrigation winterization (properly draining and shutting down your system before the first hard freeze) is also a service that protects your investment and should be scheduled each fall.
Related Resources
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