Sprinkler winterization for Greater Houston —
when to blow out, when to wait.
The hard-freeze window on the Texas Gulf Coast runs December through February, and the cold snap that cracks a backflow preventer usually arrives the same week the first 40 °F morning hits the calendar. Get the prep done before Thanksgiving and the blow-out booked before mid-December, and the worst that can happen is the controller loses its rain-sensor sync.
The freeze window is short. The prep list is shorter.
Houston’s first hard freeze usually lands between December 15 and the New Year, and the years it does not are the years that get a sudden cold snap in early March. Either way, a sprinkler system that is full of water when the temperature drops below 28 °F will crack the parts that are hardest to replace: the backflow preventer, the lateral manifold, and the controller board.
The homeowner-side prep below takes an hour. The compressed-air blow-out is the same crew that did your spring startup, runs each zone to ~80 psi until the lateral is actually empty, and walks the yard the same visit. Send a note and the office will pencil you in before the first hard-freeze weekend — not after.
- Shut off the isolation valve at the meter — turn all the way to the closed position and back off a quarter turn so the rubber seal does not freeze-set.
- Drain the low points — open the manual drain at the lowest valve, the end-of-line drains at the manifold, and any anti-drain valves that the system was plumbed with.
- Protect the backflow preventer — the above-ground PVB or RPZ is the #1 thing that cracks at 28 °F. Insulate with a foam bag or old towel and a trash bag; do not seal it airtight.
- Mark the valve boxes — a freeze-burst lateral will not show until spring startup, so a flag at each box saves the diagnostic visit on the first warm day.
- Power down the controller — set to OFF (not just RAIN OFF) and unplug the transformer from the outlet so a Gulf lightning storm does not cook the board over the winter.
- Schedule the compressed-air blow-out — the crew runs each zone to ~80 psi until the lateral is actually empty, not just until the head stops spitting. Books out by mid-December on the Gulf Coast.
Do all six before the first hard-freeze weekend. The crew will handle the compressed-air blow-out the same visit they walk the yard — usually 30 to 45 minutes for a typical Cypress or Tomball system.
A cracked backflow preventer is a $200 to $400 mid-winter parts-and-labor swap on top of the blow-out itself, and a frozen lateral that splits underground does not show up until spring startup pressurizes the system for the first time. The cheapest winter is the one where the prep went out ahead of the weather.
Who it’s for: Cypress, Katy, Tomball, and Spring homeowners with any PVC laterals, an above-ground backflow, or a controller mounted on an exterior wall.
Right window: the first week of December. Wrong window: the first 40 °F morning.
The right scheduling window for a sprinkler blow-out across Cypress, Katy, Tomball, and Spring is mid-to-late December, not the first cold morning of November. That timing lines up with the first sustained hard freeze — which on the Gulf Coast usually lands between December 15 and New Year’s — and lands you on the calendar ahead of the wave of calls that hits the office the moment the temperature drops.
The wrong trigger is the first 40 °F morning: by then the night-time forecast is already pointing at a hard-freeze weekend, and the same-week service window is gone. Get the prep list out of the way first, then send the office a note the same week — they’ll pencil you in for the first available visit before the cold snap, not after.
For a deeper read on the timing logic and the December–February freeze window, see the Gulf Coast sprinkler blow-out timing post or the full winter blow-outs service page.
Book the blow-out before the first hard-freeze weekend — the calendar fills the same week the temperature drops.
Free quote visits in Greater Houston inside a few business days. Same Cypress-based tech who did your spring startup is the one who shows up for the winterization.