The Rockies selected Blach's contract from Triple-A Albuquerque ahead of his scheduled start Sunday against the Orioles.
Colorado placed right-hander Cal Quantrill (tricep) on the 15-day injured list to open up room on the 28-man active roster and in the rotation for Blach. The soft-tossing southpaw has previously made 18 appearances (10 starts) for Colorado this season, pitching to a 3-6 record with a 6.36 ERA, 1.70 WHIP and 34:16 K:BB in 63.2 innings.