If your property has an in-ground irrigation system, it must be turned on in the spring, periodically inspected during the summer months to ensure that you aren't watering the sidewalk or the street, and blown-out and shut off in the fall before the first hard freeze occurs.
Typically, irrigation systems are turned in in late April or early May and are shut off in late September or early October. Companies will need access to your irrigation shut-off value (usually located in your basement) and your irrigation system control panel (often found in your garage) to perform services.