Garton was optioned to Triple-A Durham on Saturday, Marc Topkin of the Tampa Bay Times reports.
The right-hander labored through 1.2 frames Friday, allowing three hits and two walks while needing 38 pitches to record the five outs. Garton has struggled this season while working primarily in mop-up situations (4.73 ERA, 1.61 WHIP). Although he figures to return once rosters expand, there's little reason to think he will be entrusted with meaningful innings.