For facility managers overseeing office parks, medical campuses, or industrial properties, irrigation winterization is easy to put off until it is too late. Once overnight temperatures start dipping below freezing, water left sitting in exposed pipes, backflow preventers, and valve boxes can freeze, expand, and crack components that are expensive and disruptive to replace.
The short answer: before the first hard freeze
As a general rule, commercial irrigation systems should be winterized before the ground sees its first sustained hard freeze, typically once overnight lows consistently drop into the low 30s or below. In the St. Louis area, that usually means scheduling winterization sometime between mid-October and early November, well ahead of the season’s first deep freeze. Waiting until a freeze warning is already posted leaves little room for scheduling, and a single missed call can mean cracked pipes discovered in the spring instead of a quick fall shutdown.
Property owners can check seasonal freeze outlooks through the National Weather Service to get a general sense of when the first hard freeze typically arrives in their area, but commercial properties with large irrigation zones should build in extra lead time rather than waiting for the forecast to confirm it.
What commercial winterization actually involves
A proper shutdown is more than just turning off the water. It typically includes shutting off the main water supply, draining or blowing out water from all lines and sprinkler heads with compressed air, insulating above-ground backflow devices, and setting controllers to their off or rain mode for the season. On larger commercial systems with multiple zones, skipping even one section can leave trapped water that freezes and splits a line.
Why timing is a bigger deal for commercial properties
A residential system might have a handful of zones. A commercial property can have dozens, feeding everything from entrance beds to large turf areas that matter for curb appeal and tenant satisfaction. A cracked backflow preventer or split mainline discovered in March often means an emergency repair, a delayed irrigation start-up, and weeks of brown or uneven turf while the system is fixed, right when the property should be looking its best for spring.
Build it into your seasonal plan
The easiest way to avoid last-minute scrambling is to fold irrigation winterization into a broader seasonal grounds maintenance schedule rather than treating it as a one-off call. Bluegrass Lawn’s irrigation and sprinkler services include seasonal shutdown and spring start-up as part of ongoing commercial maintenance, so property managers do not have to track freeze forecasts themselves. If your property’s system has not been scheduled for winterization yet this fall, now is the time to get on the calendar, before the first freeze makes the decision for you.
