The short answer: two to three weeks after your last frost, once overnight lows reliably stay above 32°F and your soil has thawed to roughly 12 inches deep. Turning on too early risks freeze damage. Too late and your lawn dries out, plus every irrigation company is booked.
Done in seconds. No sign-up required.
The right date for spring start-up depends entirely on your average last frost. Use these as approximate windows, then adjust to your local NOAA last-frost date and the actual forecast in any given year.
| Region | Typical last frost | Best start-up window |
|---|---|---|
| Deep South (FL, southern TX, AZ) | Late January – February | Late February – March |
| Mid-South (NC, TN, northern TX) | March – early April | Late March – mid-April |
| Midwest, Mid-Atlantic | Mid-April – early May | Late April – mid-May |
| Northeast (NY, MA, CT) | Late April – mid-May | Early – late May |
| Mountain West, Upper Midwest | Mid-May – early June | Late May – mid-June |
A late freeze is the single most expensive sprinkler mistake. Once the mainline is pressurized and the backflow is wet, a single night dropping to 28°F can crack the brass body of the backflow preventer, split the PVC mainline, or shear off a valve diaphragm. Repairs run from $200 for a replaced backflow to over $1,000 for a mainline repair under your driveway.
The pattern that catches homeowners every year: warm week in early April, you turn on the system, then a single cold front rolls through with one night at 25°F. The damage does not show up immediately. You notice the leak in May when the lawn refuses to green up in one zone, or in your next water bill. Set your sprinkler check reminder for two to three weeks after your average last frost, not before.
Waiting until late May or June in a Midwest climate means the lawn has already started to brown out from spring drought, the soil has hardened, and you are competing with every other homeowner for an irrigation appointment. Booking windows in early April are typically wide open. By mid-May, lead times can stretch to three weeks.
The right reminder fires two weeks before your ideal start-up date. You book at the front of the season, you avoid the rush, and you give your lawn the head start it needs before the first 80°F week shows up.
Overnight lows should stay above 32°F for at least a week, and ideally above 40°F before you fully pressurize the system. A single hard freeze with the lines charged can split valves and crack the backflow preventer.
Yes, running zones in 40°F daytime weather is fine if there is no overnight freeze in the forecast. The danger is not the temperature while the heads are spraying, it is the residual water freezing inside the lines hours later.
Two to three weeks after your last expected frost. In most of the northern US that means mid-April to mid-May. In the South it can be as early as late February. Use your NOAA last-frost date plus a buffer, not the calendar date.
No, 4am to 6am is the recommended watering window. The lawn has time to dry before evening, water loss to evaporation is minimal, and pressure is highest because demand on the city main is at its lowest. Avoid running heads in the middle of the night when freezes can still hit.
Open the main valve slowly to let air bleed out, check the controller settings and replace the backup battery, walk every zone to confirm heads pop up correctly, watch for leaks at the backflow and valve boxes, and adjust the schedule for current weather. The Lawn Sprinkler Start-Up Checklist is the standard reference.
Two weeks before your average last frost. That gives you time to book a service slot before every irrigation company in your area is booked out three weeks deep, or to schedule your own DIY morning when the weather cooperates.
Free. No account. Two weeks of lead time before your last frost — enough to book a slot, walk the zones, or call the pro before the spring rush.
Create Spring ReminderLast modified: