Areas north of the transition zone need to prepare for icy, frozen winters. This means that underground, sprinkler systems need to be blown out with compressed air and at the very least, hoses need to be emptied of excess water and put away.
Winterizing an underground sprinkler system is easy if you have the proper equipment. The most important piece is an air compressor. If you don't have one, you can rent one, and if a lawn company can't do it, they can recommend someone who can.
The water source is turned off and the system is drained of as much water as possible. An air compressor is connected to the piping and forces air and the remaining water out of the sprinklers. Each station is gone through several times to ensure only air is being blown through the sprinkler heads.
Sprinklers and Hoses
Sprinklers and hoses need special attention too. Water can freeze inside sprinkler housings and hoses and burst or rupture parts.
Sprinklers should be cleaned and stored out of the way in a dry place. Hoses should be disconnected from water source and drained of any remaining water. Hoses should then be neatly coiled and stored in a dry, out of the way area.