Johnson joined the Cardinals on July 8, and he has had three hits over 19 at-bats. With Moss, Mark Reynolds and Stephen Piscotty able to provide coverage at first base, Johnson would have been squeezed out of playing time.
Garcia is joining the Cardinals for the second time this season. He appeared in 12 games from June 19 to July 3, and he went 5-for-12 with his first Major League home run. In 81 Triple-A games this season, Garcia is hitting .299 with a .404 on-base percentage.
Both Garcia and Moss are expected to be in uniform for Thursday's game.