My largest male is approaching 3 feet and my largest Albino female is somewhere between 3.5 to just under 4 feet. Checkereds can get pretty big by Thamnophis standards. At shows I get a lot of "wait..that is a GARTER snake? I thought it was a Corn..."

As stated already, they breed pretty easily. Usually without anything more than just putting them together and letting nature take it's course.