Garrett (biceps) began a rehab assignment for Single-A Fredericksburg on Saturday and allowed one hit over a scoreless inning.
Garrett was placed on the 15-day injured list July 7 with right biceps inflammation, and the short-term nature of his absence suggests that he likely won't require much ramp-up time in the minors. Once he's activated, Garrett will likely handle a low-leverage role out of the Washington bullpen.