Single-A Fredericksburg placed Harmon on the 7-day injured list May 7 with a left oblique strain, Geoff Pontes of Baseball America reports.
Harmon, who last pitched April 24, logged a 1.88 ERA, 0.91 WHIP and 11:5 K:BB in 14.1 innings across four starts to begin his pro career before suffering the injury. The projectable 6-foot-5 righty was one of the top prep arms available in last year's draft.