The Labor Day director - who worked with Winslet and Josh Brolin on the film - told Empire that he feels privileged to have worked with the British star.
Reitman took the decision to wait for Winslet before shooting Labor Day, after she decided to take a break from Hollywood.
He explained: ''Kate Winslet is one of the greatest actresses living today, and that there will ever be. If I've got a script that Kate Winslet is willing to say yes to, I will wait a year, I will wait five years.
''If Kate had said, 'F**k this s**t', I would have found someone else. But, for the rest of my life, I get to say I directed Kate Winslet. It's huge.''
Labor Day - adapted from Joyce Maynard's novel of the same name - centres on 13-year-old Henry Wheeler, who struggles to be the man of his house and care for his reclusive mother Adele (Winslet) while confronting all the pangs of adolescence.
During a shopping trip, Adele and Henry encounter an intimidating, injured man (Brolin), and against her better judgement she invites him to stay in her home.
Gattlin Griffith stars as Henry, while Tobey Maguire plays an older incarnation of him.
The film will open on January 31 in the US and February 7 in the UK.
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