The school said in a statement Friday that Gary had successful surgery on his right knee Thursday and is expected to make a full recovery.
The four-star prospect is the Crimson Tide's second newcomer to go down with a preseason injury. Junior college forward James Rojas also sustained a knee injury and is expected to miss the season.
Gary was ranked by ESPN as the No. 64 player in his recruiting class and the 12th-best small forward.
He averaged 25 points last season at Liberty Heights High School in Charlotte, North Carolina.
Alabama is led by first-year coach Nate Oats.