Spring Sprinkler Startup Guide for Idaho
After five months of dormancy, your sprinkler system needs a careful, methodical restart. Rush it and you risk water hammer damage, missed leaks, and wasted water. Follow this guide for a trouble-free spring startup.
When to Turn On Sprinklers in Idaho
The golden rule is simple: wait until after the last hard frost. In Eastern Idaho, spring comes later than many homeowners expect. Even in April, overnight temperatures can drop below freezing, and a hard freeze after you've charged your system with water means the same pipe-cracking risk you winterized to avoid.
Important: These are averages. Always check the 10-day forecast before turning on your system. If overnight lows below 32°F are predicted at any point in the next week, wait. One unexpected late frost can undo all the protection your fall winterization provided.
Step-by-Step Spring Startup Procedure
Visual Inspection Before Turning On Water
Walk your entire yard and visually inspect every component you can see. Check the backflow preventer for cracks or frost damage. Look at valve boxes — are the covers intact? Has settling or frost heave exposed any pipes? Check each sprinkler head location — are heads tilted, sunken, or damaged from snow removal or foot traffic? Note any issues before adding water pressure.
Remove Winter Insulation
Remove insulation wraps, bags, and covers from your backflow preventer and any exposed pipes. Store them somewhere dry for reuse next fall. Inspect the components underneath — look for hairline cracks, loose fittings, or green oxidation on brass fittings that could indicate a slow leak formed before winterization.
Close All Drain Valves
If you opened manual drain valves during winterization, close them now. Forgetting this step means water will pour out of the drain points instead of reaching your sprinkler heads. Check each drain valve location — there may be 2–4 throughout the system.
Slowly Open the Main Shut-Off Valve
This is the most critical step. Turn the main irrigation valve open very slowly — no more than a quarter turn at a time, waiting 30–60 seconds between turns. This gradual pressurization prevents water hammer, which can crack pipes and blow fittings. Full pressurization should take 5–10 minutes. Listen for any unusual sounds — banging, hissing, or rushing water where there shouldn't be any.
Check the Backflow Preventer
Once pressurized, inspect the backflow preventer closely. Look for dripping, spraying, or pooling water around the base. A small amount of weeping from the test ports is normal during initial pressurization. Sustained leaking means a seal failed over winter and the unit needs service.
Test Each Zone Manually
Using your controller, run each zone manually for 3–5 minutes. Walk the entire coverage area of each zone while it runs. Check every head: Is it popping up fully? Is the spray pattern correct? Any heads spraying sideways, not rotating (rotors), or not popping up at all? Look for geysers (broken heads), soggy areas (pipe leaks), or dry spots (clogged nozzles).
Adjust and Repair
Based on your zone-by-zone inspection, make adjustments. Straighten tilted heads by digging around the base and repositioning. Clear clogged nozzles by unscrewing the head top and rinsing the screen filter. Replace broken heads ($5–$25 each at any hardware store). If you find a pipe leak, mark the location and either repair it yourself or call a professional.
Program Your Controller for Spring
Spring watering needs are lighter than summer. Start with 2–3 days per week, running each zone for 15–25 minutes in the early morning (4–6 AM is ideal). As temperatures climb into June, increase frequency. If you have a smart controller, update the app and let it auto-adjust based on weather data. Our smart controller guide has detailed scheduling recommendations.
Checking for Winter Damage
Even properly winterized systems can sustain damage from Idaho's harsh winters. Here are the most common issues to watch for during spring startup:
- Frost-heaved heads: Freeze-thaw cycles push heads up out of the ground. They'll need to be dug out and reset at the correct height.
- Cracked backflow preventer: Look for hairline cracks in brass bodies. Even small cracks will leak under pressure.
- Shifted pipe connections: Frost heave can pull pipe joints apart underground. Watch for unexpectedly soggy areas when zones run.
- Damaged valve diaphragms: If a zone won't turn off (water keeps flowing after the controller shuts it down), the valve diaphragm may be damaged.
- Rodent damage: Mice and voles sometimes chew through drip tubing and low-voltage controller wires over winter.
For help diagnosing problems, see our Sprinkler Troubleshooting Guide. If damage is extensive, request a repair quote from NewHome Finishers — addressing problems early prevents wasted water and bigger issues later.
Controller Programming for Spring
Your spring watering schedule should ramp up gradually. Idaho lawns are still coming out of dormancy in May and don't need the heavy watering they'll require in July and August. Here's a general spring schedule for Eastern Idaho:
These are starting points — your actual schedule depends on soil type, sun exposure, grass variety, and slope. Smart controllers eliminate the guesswork by automatically adjusting based on real-time weather data and local evapotranspiration rates. If you're still using a basic timer, spring startup is a great time to upgrade. See our zone planning guide for detailed watering calculations.
Professional Spring Startup Service
A professional spring startup typically costs $50–$75 and includes system pressurization, zone testing, head adjustment, controller programming, and a visual inspection for damage. Many irrigation companies offer a winterization + spring startup bundle at a discounted rate. If you're not comfortable doing the startup yourself, or if you want a trained eye to spot potential problems, it's a worthwhile investment.
Need Help with Spring Startup?
NewHome Finishers connects you with experienced irrigation pros for startup service, repairs, and system upgrades across Eastern Idaho.
Get Your Free Quote →