When to Turn On Irrigation in Denver (And What to Check First)
Colorado spring weather can be unpredictable. Warm afternoons often give way to freezing overnight temperatures well into April—and occasionally beyond. Turning on your irrigation system too early can lead to cracked backflow devices, broken sprinkler heads, burst fittings, and avoidable repairs.
For Denver-area homeowners, timing matters. Here’s when to turn on your irrigation system, what to inspect first, and how to protect your landscape investment heading into the growing season.
What’s the Right Time to Turn On Irrigation in Denver?
For most Denver properties, irrigation systems are typically activated mid-April through early May, depending on weather patterns and elevation.
The safest benchmark is a consistent stretch of overnight lows above freezing, with no hard freeze in the 7–10 day forecast.
Neighborhoods at higher elevations or exposed areas may need to wait longer.
At Waymark, we recommend patience over premature startup. One late freeze can cause more damage than waiting an extra week.
Why Denver Timing Is Different
Denver’s climate creates unique spring challenges:
Rapid temperature swings
Late snowstorms
Freeze/thaw cycles
Dry, windy spring conditions
Different microclimates across neighborhoods
A Cherry Hills property may warm differently than a foothills lot in Golden or Castle Pines. Irrigation startup should be based on your property—not just the calendar.
What to Check Before Turning On Your System
1. Review the Forecast
Look for:
Overnight temperatures consistently above 32°F
No hard freeze expected
Stable weather for at least a week
If another cold snap is coming, wait.
2. Walk the Property
Before restoring water pressure, inspect for:
Broken sprinkler heads
Shifted nozzles
Exposed drip lines
Winter settlement near valves
Damage from snow removal or foot traffic
Spring is the ideal time to catch minor issues before they become larger repairs.
3. Inspect the Backflow Preventer
Your backflow preventer protects your drinking water supply and is one of the most freeze-sensitive components in the system.
Check for:
Visible cracks
Leaks
Rust or corrosion
Loose fittings
If damaged, do not pressurize the system.
4. Confirm Proper Winterization Last Fall
Systems that were not professionally blown out in fall are at higher risk for hidden freeze damage.
Common spring surprises include:
Split lateral lines
Cracked valves
Leaking manifolds
Damaged emitters
5. Turn Water On Slowly
When reactivating:
Open valves gradually
Avoid sudden pressure surges
Test zones one at a time
Watch for leaks or misaligned spray patterns
A rushed startup can create unnecessary failures.
Signs You Should Call a Professional
Consider professional startup if you notice:
Water pooling
Low pressure
Broken heads
Controller issues
Leaks at backflow device
Uneven coverage
Zones not activating
Why Professional Irrigation Startup Often Pays for Itself
A proper spring irrigation startup can:
Prevent expensive repairs
Improve watering efficiency
Reduce runoff
Protect plant material
Save water
Catch hidden issues early
For larger estates or professionally designed landscapes, this is especially valuable.
Waymark Stewardship: Seasonal Irrigation + Property Care
For select Denver-area clients, Waymark offers seasonal irrigation startup, inspections, adjustments, and broader property care through our Stewardship services.
We help clients protect and maintain outdoor environments with the same design-minded attention that built them.
Final Thought
In Denver, the right time to turn on irrigation is not the first warm weekend—it’s when the weather has truly turned.
A thoughtful startup protects your system, supports healthy growth, and sets the tone for the season ahead.
Need help with irrigation startup, repairs, or spring property preparation? Contact Waymark Outdoor Design to schedule seasonal service.
