When does Heartland return?

Heartland is an American medical drama television series that aired on TNT from June 18 to August 31, 2007. The series was based in the high-stakes world of heart-transplant surgery at "St. Jude" hospital in Pittsburgh based largely on the transplant center at the University of Pittsburgh Medical Center. It followed a recently separated couple who work both sides of the trade.
B. L. McCutcheon, an old-fashioned farmer, loses his farm and has to move in with his daughter's family in the fictional rural town of Pritchard, Nebraska.