In an interview published by InStyle on Thursday, the 22-year-old actress revealed she was asked by producers not to wash her hair while filming the HBO series, and that it went on for years.
"For the first few seasons I was allowed to wash my hair because I was an aristocratic young girl. Towards season five, they started asking me to not wash my hair and it was really disgusting," Turner said, confirming that several male actors on the show received the same request.
"Now I wear a wig, so I can wash my hair whenever I want, which is nice. But yes, for a couple of years I was living with pretty greasy hair."
"[It was] really itchy! Also, we would have the snow machines going so we would have little snow paper particles that would get stuck in the grease. It was disgusting," she added.
Turner is a natural blonde and dyed her hair for years to become Sansa. It wasn't until 2017 that she went back to her natural color, which has saved her hair from damage on "Game of Thrones" but added time to her hair-and-makeup schedule.
"It's mainly the people with the wigs that take the longest," she explained, adding that Emilia Clarke probably had the most intensive hair routine "because she needed a bald cap, a wig, and then had an intricate design on the wig ... [but then she] dyed her hair blonde!"
Turner said Kit Harington has the most intensive hair routine off-screen: "Before red carpets you would always see him scrunching the ends of his curls to make sure they're perfect. We all take the piss out on him for that," she joked.
Turner says she's looking forward to fans seeing the cast's on-screen hair transformations in the show's upcoming eighth and final season.
"For so long, Sansa’s hair changed season by season depending on who was influencing her," she said.
"The first few episodes she was a Northerner in Winterfell and took after her mother with a simple braid down the back. Then when she went to King’s Landing it was a big, decadent halo that was very much like what the Queen wore. With Littlefinger, she dyes her hair black and wears all black. Then she goes back to Winterfell and returns to her mother’s hair."
"She created her own identity in season seven and that kind of runs through to season eight," Turner continued. "She’s chosen how she wants her hair to be, and she’s finally the leader and influencer instead of being influenced by everyone else."
As for how things end up on the final season, Harington recently told the Zoe Ball Breakfast Show that he's “maybe not happy, but very satisfied” with "Game of Thrones" ending.
"I'm so excited for people to see it," he said. "I think it's going to be extraordinary; hopefully it'll change TV again like it did originally, and break boundaries. I think it might."