Alia Bhatt is going to turn 25 on March 15 and will spend the day shooting for Ayan Mukerji’s ‘Brahmastra’. The actress has been working on the action adventure with Ranbir Kapoor and Ayan in Bulgaria. “It’s a hectic schedule so she can’t afford a day off but there will definitely be a celebration on set,” revealed a source. Ranbir and Ayan are reportedly planning a big bash on the film’s set to celebrate Alia’s big date. Producer Karan Johar was planning to join the team of ‘Brahmastra’ on Alia’s birthday on Thursday but has stalled his plans for another birthday bash. Karan Johar’s mother Hiroo will turn 75 on Sunday and KJo is planning a big party for his mother.