The 44-year-old said the director left the responsibility of her character's meticulously groomed wardrobe in her hands.
Blanchett then with the help of costume designer Suzy Bezinger crafted the disgraced Manhattan socialite, Jasmine, reported Vogue magazine.
"He's been wearing the same Ralph Lauren sweatpants and T-shirt for the last 20 years and doesn't understand why anyone would change their wardrobe according to their mood, or how they want to present themselves. He just doesn't get it," she said.
"There's a tragedy to her clinging onto those threadbare things - a bit like Blanche DuBois, trying to make herself as attractive and alluring as possible. Like Blanche, she has such a romanticised sense of self. Because of the internal pain, sometimes it's easier to exist in a world of fairy lights and fantasy.
"One of the primary industries in America is fantasy, and so there's a naivety behind that. And I think that makes Jasmine an anti-hero of her time in her way," she added.
"Blue Jasmine" is in cinemas nationwide from September 27.