There is quite a bit of confusion between winterizing and blowing out a sprinkler.  They are often used synonymously, but they aren't quite synonymous. Blowing out a sprinkler is winterizing, but winterizing isn't always blowing out. 

A sprinkler blow out is when a large air compressor (185 psi or larger) is connected through a valve in your sprinkler system that physically blows the water out of your sprinkler through the sprinkler heads. This process is required if your sprinkler system was installed with PVC pipe. This is more common on systems larger than 12 zones.

A standard winterization is a sequence of steps taken on a properly installed poly pipe system to allow the water to drain out. There is no such thing as a self-winterizing or self-draining sprinkler. There are steps that need to be taken every fall to prevent freeze damage to your system. See Winterizing your Sprinkler System for steps. 

Most sprinkler systems in Siouxland do NOT need to be blown out.  Several years back there was a company that only installed PVC pipe-based systems in South Sioux City and there is a larger pocket of air- compressor required winterizations in that area.  There are areas in the USA where all the sprinklers are installed with PVC pipe, but that isn't the case here. As a matter of fact, less than 1% of the residential sprinklers we maintain on an annual basis require an air compressor winterization and only three of those residential sprinklers are Jensen Sprinkler installations.

How do you know?