Spring Sprinkler Startup in Colorado: When to Turn On and What to Check

In Northern Colorado, the safest time to turn on your sprinkler system is late April to early May, after nighttime temperatures stay consistently above 32 degrees for at least a week. Turning on too early risks freeze damage to pipes and backflow preventers, which can cost $500-$1,500 to repair.

Here's when to actually do it and what to check before you let it rip.

When to Turn On: Late April to Mid-May

I know it's hard to wait, but here's the reality. In Erie, Longmont, and across the Front Range, we regularly get overnight freezes through mid-April. Some years we get snow in May. If your system is pressurized and water is sitting in the lines during a hard freeze, you're looking at cracked pipes and split fittings.

Our rule of thumb: don't turn on until nighttime temps are consistently above 32 degrees. That usually means late April at the earliest for most of the Front Range. If you're at higher elevation or in a frost pocket, push it to early May.

Your lawn can handle a few weeks of looking dry. It's dormant. It'll green up once you start watering. But a cracked mainline or busted backflow preventer is a $300-$800 repair.

What a Proper Startup Looks Like

Whether you do it yourself or hire it out, here's the right sequence:

Step 1: Check the backflow preventer. Look for cracks, loose fittings, or anything that looks off. The test cocks should be closed. If your preventer is above ground and took a hit from winter, you'll see it here.

Step 2: Slowly pressurize the system. Don't just crank the main valve open. Open it a quarter turn and let the system fill slowly over 5-10 minutes. This prevents water hammer (that loud banging in the pipes) which can crack fittings and blow seals.

Step 3: Run each zone manually. Go through every zone one at a time from the controller. Walk the yard while each zone runs. You're looking for:

• Heads that don't pop up
• Heads that spray erratically or don't rotate
• Water bubbling up from the ground (underground leak)
• Dry spots where heads should be covering
• Heads aimed at pavement

Step 4: Check the controller settings. If you lost power over winter, your controller may have reset to factory defaults or lost its programming entirely. Battery backup helps, but batteries die. Reprogram your schedule or set your smart controller to start its seasonal adjustments.

Step 5: Check for leaks at connections. Look at every visible connection point: the backflow preventer, the main shut-off, and any above-ground fittings. Small drips now become big problems later.

Common Problems We Find Every Spring

We do hundreds of spring startups across Erie, Longmont, Louisville, and Lafayette. Here's what we find most often:

• Cracked pipes from freeze damage. Even if you winterized, sometimes water gets trapped in a low spot. You won't know until you pressurize and see water pooling in the yard.
• Heads knocked off by snowplows. If you have heads near the driveway or sidewalk, plow blades and snow shovels hit them all winter. We replace 5-10 heads on spring startups regularly.
• Controller lost its programming. The backup battery died, power flickered, or someone accidentally reset it. If you have a smart controller like a Rachio, it stores everything in the cloud so this is less of an issue. Old-school timers? You're reprogramming from scratch.
• Valve diaphragms stuck from sitting all winter. Valves that sat dry for six months sometimes don't open or close properly on the first run. Running each zone a couple times usually frees them up. If not, the diaphragm might need replacing ($75-$150 per valve).
• Backflow preventer damage. This is the big one. Backflows sit above ground and take the worst of winter. Cracked bodies or blown internal seals need replacement, and in most Front Range towns, you need a certified test on your backflow every year anyway.

DIY Startup vs Hiring It Out

If you're handy and comfortable with your system, you can absolutely do a spring startup yourself. Follow the steps above, go slow, and pay attention.

Hire it out if:

• You don't know where your shut-off valve or backflow preventer is
• Your system is more than 10 years old (higher chance of problems)
• You had any issues last fall before winterization
• You want someone to catch problems before they become expensive

A professional spring startup runs $75-$125 for most residential systems. We pressurize, run every zone, check every head, inspect the backflow, and flag anything that needs attention. It takes about 45 minutes to an hour.

That's cheap insurance against a surprise $500 repair bill in June when you finally notice the soggy spot in the backyard has been leaking for two months.

Don't Rush It

I get it. You want a green lawn. But a few weeks of patience in April saves you real money and headaches. Wait for consistent warm nights, go slow on the pressurization, and walk every zone.

Trailhead Lawn & Irrigation offers spring startup service across Erie, Longmont, Louisville, Lafayette, Frederick, and Firestone. We start booking startups in early April and the schedule fills fast. Give us a call to get on the list.