Fall Blowout Checklist: What We Tell Homeowners Before the First Hard Freeze

Timing depends on your last frost date, not the calendar app on your phone. In shoulder climates we often wait until overnight lows threaten the mid-20s °F. Blow out too early and you still run the system for fall overseed; blow out too late and you are repairing PVC.

1. Shut the main irrigation supply and relieve pressure at a hose bib or drain.
2. Open each zone briefly with the compressor — watch for mist, not a continuous geyser that can damage seals.
3. Power down the controller or set it to off; do not leave a schedule running into empty pipes.
4. Note any valve that failed to open — that is a spring repair, not a surprise in April.

DIY compressors work for small lots. Larger properties with long mainlines are usually cheaper as a service call than as a cracked fitting hunt.