The team decided on Monday to slow down the process with four weeks remaining until opening day. Castro incurred the injury on Feb. 27 during Cactus League play while running out a ground ball and has not played since.
Castro has participated in light drills since getting injured and took ground balls and some batting practice on Monday.
Cubs manager Dale Sveum told reporters Monday that if this was the regular season Castro could certainly play.
Castro signed a seven-year, $60 million contract with the Cubs last summer. Castro played in all 162 games in 2012.