The injury, suffered in a warm-up game last week, has proven more severe than first anticipated, said Stormers coach Robbie Fleck on Thursday.
"The outcome with him and his injury is that is still four to six weeks," Fleck said he named his team for their first game in this year’s edition away against the Bulls at Loftus Versfeld in Pretora.
"He took a cleanout against Boland and did his hamstring. It's a grade two tear.”
Kitshoff, who turned 27 this week and has won 37 test caps, joins fellow Springbok prop Frans Malherbe, locks Eben Etzebeth and Cobus Wiese, loose forward Juarno Augustus and wing Sergeal Petersen on the Stormers' injury list.
All apart from Kitshoff and Etzebeth are expected to be available for the game at home to the Lions on Feb. 23.
(Reporting by Mark Gleeson; Editing by Toby Chopra)
