<P> Rumors began back in 2012 about a possible return of Katherine Heigl's character Izzie Stevens to Grey's Anatomy after Heigl expressed her desire to return for an arc to complete Izzie's story . In May 2015, rumors began to swirl that Heigl would return for the twelfth season . Michael Ausiello from TVLine speculated on the return as he thought the upcoming twelfth season would be the perfect opportunity for Heigl to return to the show . He wrote that "the show needs a jolt of old - school energy to improve its vitals going into Season 12, and an Izzie comeback would be just what the doctor ordered ." Heigl declined the rumors of returning to the show's current season in an interview with Entertainment Tonight . At the ABC's Television Critics Association press tours, Rhimes declined the rumors as she explained her reasons: "I'm done with that story . I've turned that idea over in my mind a thousand times and thought about how it would go . And I don't think so ." </P> <P> The season marked the last appearance for long - time cast member Sara Ramirez who played Dr. Callie Torres on the series since 2006 . Her character was involved in a custody battle with ex-wife Dr. Arizona Robbins, played by Jessica Capshaw, which led to the former's move to New York from Seattle . On May 19, in a note posted on Twitter after the season finale, Ramirez wrote that she was "taking some welcome time off ." Rhimes replied to the tweet by saying, "I will miss Callie tremendously, but am excited for what the future holds for Sara . She will always have a home at Shondaland ." Later, speaking at the Vulture Festival in New York City on May 22, Rhimes, told that she didn't know that Ramirez was leaving until they had shot the finale . She addressed Callie's send - off and said, "This one was different because it wasn't a big planned thing, I had a different plan going and when Sara came in and said,' I really need to take this break,' I was lucky that we'd shot the end of the season with her going to New York ." </P> <P> Prepping for the season began on July 13, 2015 . The table read for the premiere was on July 15, 2015 . Filming began on July 22, 2015 . Two - time Academy Awards winner Denzel Washington was announced by TVLine to direct the ninth episode of the season, which will be Washington's first go at directing television . He previously directed the films Antwone Fisher and The Great Debaters . </P> <P> The number in the "No. overall" column refers to the episode's number within the overall series, whereas the number in the "No. in season" column refers to the episode's number within this particular season . "U.S. viewers in millions" refers to the number of Americans in millions who watched the episodes live . </P>

When was season 12 of grey's anatomy filmed
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