I called the Dexter Blueberry Farm this morning to get the opening date of the blueberry picking season. The recorded hotline (734) 426-2900 gave the first day of picking of the year as "no later than July 18". The web site says that the season generally goes through September 10, and U-Pick is $1.35/lb.
The farm is at 11024 Beach Road, between Dancer Road and Lima Center Road north of Dexter-Chelsea Road between Dexter and Chelsea. Take I-94 Exit 162.