Question
When should I aerate my lawn here in Boise?  I'm pretty sure it needs it.

Response
Lawns should be aerated in the spring or fall.  We want to aerate the turf when the soil is cool.  Your turf put on a massive root growth in the spring and fall during the cool soil temperature.  Aeration does some damage to the roots. Your turf will repair itself at this cool soil period.  Be sure to use a core aeration machine to get the most benefit from your work.  Mark all sprinkler head in the lawn.  A core aeration machine and sprinkler heads are not a good match.  Don't worry about removing the plug that are on the top of the turf, they will break down and add some organic content back to the soil.  Be sure  to apply some lawn food after you aerate to speed up the process of the lawn repairing itself.