Spring Sprinkler Start-Up Checklist: Get Your Denver Irrigation System Ready

As Denver emerges from winter, your sprinkler system needs attention before the first hot day arrives. A proper spring start-up protects your investment, prevents costly repairs, and keeps your lawn lush all season. Here is your complete checklist from Apex Irrigation.

Step 1: Inspect and Test Your Irrigation Controller

Your irrigation controller is the brain of your system, and after sitting dormant through a Denver winter, it needs a quick checkup before you do anything else. Start by opening the controller cabinet and looking for any signs of moisture damage, corroded terminals, or pests that may have nested inside. If your controller runs on a backup battery — most do — replace it now. A dead backup battery means your entire programmed schedule gets wiped out if the power flickers, and in Colorado, spring storms can cause exactly that.

Next, review your zone programming. Check that the days, start times, and run durations are still set correctly — it is not uncommon for settings to shift after a winter power outage. Homeowners in Highlands Ranch and throughout the Denver metro area should note that programming varies depending on grass type, sun exposure, and soil conditions. Turf in full sun typically needs more frequent watering than shaded beds, so make sure each zone is set appropriately. If you are unsure how to navigate your specific controller model, the manual is usually available online by searching the brand and model number.

Step 2: Turn On the Main Water Shut-Off Valve Slowly

Once the controller is checked, it is time to restore water to the system — but how you do it matters. Locate your main irrigation shut-off valve, which is typically a ball valve or gate valve in your mechanical room, crawl space, or along the exterior of your home near the foundation. The key rule is to open it slowly. Turn the valve a quarter turn, wait 30 seconds, then continue opening it gradually until it is fully open.

Opening the valve too fast causes a phenomenon called water hammer — a pressure surge that travels through the pipes like a shockwave. In Colorado, this is a real concern because our clay-heavy soils shift throughout the year, which can leave pipes slightly stressed or misaligned. A sudden pressure surge after winter dormancy can blow fittings, crack PVC pipe joints, and send a repair bill your way before you have even watered your lawn once. Taking 60 to 90 seconds to slowly open the valve costs you nothing and protects your entire system.

Step 3: Check Each Zone Manually

With the water on, it is time to walk your property and test each zone individually. Go to your controller and activate zone 1, then head outside to watch what happens. Let each zone run for 2 to 3 minutes — long enough to see any problems but short enough that you are not wasting water while your system is still being evaluated.

As you observe each zone, look for three things. First, broken or missing sprinkler heads that are shooting water in the wrong direction or not popping up at all. Second, dry spots in the lawn where water is clearly not reaching — a sign of a clogged nozzle, low pressure, or a head that has settled too deep into the soil. Third, standing water or soggy areas that could indicate a broken lateral line or a head that is no longer sealing properly when the zone shuts off. Take notes on each problem zone so you can address them in the following steps.

Step 4: Inspect and Adjust Sprinkler Heads

Once you have identified the problem areas in your zone testing, it is time to get hands-on with the sprinkler heads themselves. The most common issues after winter are clogged nozzles, tilted heads, and heads that have shifted their arc or radius due to freeze-thaw cycles in the soil.

For clogged nozzles, simply unscrew the nozzle from the head while the zone is off, rinse it under a hose, and reinstall. For Rain Bird rotors and spray heads, many nozzles are color-coded by radius and flow rate, so make sure the right nozzle is on the right head. Hunter I-Core and PGP rotors have adjustable arc stops built into the head — a flat-blade screwdriver is usually all you need to correct the arc. Toro precision spray nozzles and rotors work similarly, with arc adjustments made by turning a small adjustment socket on top of the head.

For tilted heads, dig around the base of the head with a small trowel, straighten it by hand, and backfill the soil firmly around it. The top of the head should sit flush with or just below the surface of the lawn so mower blades pass safely over it. If a head is cracked or physically broken, replacement heads are available at most local hardware stores and are straightforward to swap out.

Step 5: Look for Leaks at Valves and Fittings

Even if all your sprinkler heads look fine, hidden leaks at valves and underground fittings can waste hundreds of gallons of water and go unnoticed until you get your Denver Water bill. After activating your system for the first time each spring, take a few minutes to check your valve boxes and manifold areas.

Open each valve box — the green or black plastic boxes flush with the ground in your yard — and look for water pooling inside. A small amount of condensation is normal, but standing water or mud inside a valve box is a red flag. Check the solenoids (the small cylinders on top of each valve) and the valve body itself for visible cracks or leaks. Inspect the manifold, which is typically located near your mechanical room or in a large valve box near the home, looking for drips at threaded fittings, glued joints, and around the backflow preventer.

Also walk the turf in each zone while it is running and look for areas of unexpectedly wet or spongy ground. A sunken or soft patch in the middle of your lawn with no visible head nearby often signals a broken lateral line underground. These leaks are not always obvious, but catching them early prevents foundation saturation, lawn erosion, and the kind of water waste that puts you out of compliance with Denver Water guidelines during dry stretches.

Step 6: Program Your Watering Schedule for Denver’s Summer

With your system running and your heads adjusted, it is time to set a watering schedule that fits Denver’s actual summer conditions. Getting this right upfront means healthier turf, lower water bills, and staying within Denver Water’s seasonal guidelines.

Denver Water typically implements odd-even or day-of-week watering restrictions during peak summer months. Under these rules, addresses with odd street numbers water on certain days and even addresses on others, and watering is generally prohibited between 10 a.m. and 6 p.m. when evaporation is highest. Even if restrictions are not currently in effect, following these time-of-day guidelines is a good practice year-round since watering early in the morning — between 4 a.m. and 9 a.m. — minimizes evaporation and reduces the risk of fungal disease on your lawn.

For run times, a good starting point for Denver-area lawns is 10 to 15 minutes per zone for spray heads and 20 to 30 minutes for rotor zones, 3 days per week. However, the right schedule depends on your soil type, grass variety, sun exposure, and the time of year. Many modern controllers — including smart Wi-Fi models — have an evapotranspiration (ET) or seasonal adjustment feature that automatically increases or decreases run times based on local temperature and humidity data. If your controller has this feature, enabling it now can save you significant water over a Denver summer without you having to constantly adjust the schedule by hand.

Let Apex Irrigation Handle Your Spring Start-Up in Denver

Working through this checklist yourself is absolutely possible, but if you would rather have a licensed professional handle the job, Apex Irrigation has been activating sprinkler systems across the Denver metro for 16 years. We serve homeowners throughout Highlands Ranch, Lone Tree, Parker, Centennial, Aurora, Littleton, and the surrounding communities. Our spring start-up service covers controller inspection, slow system pressurization, full zone testing, head adjustments, leak checks, and schedule programming — everything in this checklist and more. Call us today at (303) 668-0126 to schedule your spring sprinkler start-up and get your system dialed in before the heat arrives.