"We have him on a schedule, and it partially depends on when the team is at home and when the team is on the road and what kind of trip it is and all that," Luhnow said. "We'll obviously monitor him and all that. It's different than coming back from a medical situation when you have to get daily checkups to make sure he's OK. We know he's OK. He's been playing in Florida."
Singleton, a left-handed-hitting first baseman, hit .284 with 21 homers and 79 RBIs in 131 games last year with Corpus Christi and was expected to push for playing time on the Major League club this year. The Astros acquired Singleton and three other players from the Phillies in the Hunter Pence trade in 2011.
When asked if Singleton could reach the Majors this year, Luhnow cautioned that he had yet to even play at Triple-A.
"I never assume someone is going to make that jump successfully out of the gate," Luhnow said. "Ultimately he will, but he's got to demonstrate to us he can handle that environment and pitching before we move him up here."
Brian McTaggart is a reporter for MLB.com and writes an MLBlog, Tag's Lines. Follow @brianmctaggart on Twitter. This story was not subject to the approval of Major League Baseball or its clubs.