Detwiler still is not close to throwing, but he was set to run in the outfield on Friday and Saturday.
"Crank it up, let's go," Johnson said. "But we'll be very cautious with him. I would like him to pitch before the year's out, see how he is."
Ohlendorf, on the 15-day DL with right shoulder inflammation, is scheduled to make a rehab start with Triple-A Syracuse on Saturday, with limits of four innings or 65 pitches. Nats players typically complete rehab assignments at an affiliate closer to Washington, but in this case, Syracuse is the only affiliate that has a home game on Saturday.
Ohlendorf threw what Johnson said was a "great" bullpen session on Wednesday. He has been on the DL since Aug. 4, with that move retroactive to Aug. 1.
Andrew Simon is a reporter for MLB.com. Follow him on Twitter @HitTheCutoff. This story was not subject to the approval of Major League Baseball or its clubs.