Install an Underground Sprinkler System – Lowe’s Home …

You may need to prepare your system for winter to avoid damaging or breaking pipes and connections. In temperate and warm regions, you may get away with simply covering above-ground piping with insulation (in these climates, the ground doesn't get cold enough to freeze). For colder climates, this winterization process can be a DIY job, but especially for larger landscapes, it might be beneficial to hire a professional.

To ensure your system is properly protected check with owner's manual or with the manufacturer for best practices.

To Winterize:

1. Check to see if your system has auto-drain valves. If so, simply turn off water supply, open valves and allow excess water to drain from the system. This one step is sufficient to winterize underground irrigation systems with auto-drain.

2. If you have manual drains you will need to use an air compressor with pressure between 50-100 PSI. Small air compressor with lower PSI will not be able to clear water from your system.

3. Open valve manifolds to allow any remaining water to drain.

4. Hook air compressor and run air through each the zone in your system until you've cleared all zones of water.

5. Be sure to remember to turn off timer to avoid additional water from entering the system.

Read more:
Install an Underground Sprinkler System - Lowe's Home ...