The Rangers announced the move before their 7-3 victory over Boston on Sunday. It is the second time Harden has been on the disabled list this season with Texas, and the ninth time in six seasons for the right-hander.
Harden (4-4, 5.45 ERA in 15 starts) had made only two starts since missing 42 games with a left gluteal muscle strain. Outfielder Brandon Boggs was recalled from Triple-A Oklahoma City.
Boggs provides outfield depth after Nelson Cruz came out of Saturday night's game with a tight hamstring. Cruz said he was feeling better Sunday, but the right fielder did not play in the series finale against the Red Sox.
Instead of waiting another day as planned, Cruz had an MRI on Sunday and then was on the team flight to Tampa. The test showed no tear, but the Rangers said Cruz would be re-evaluated before the series opener against the Rays on Monday.
"We have to make sure that this doesn't get worse," Rangers manager Ron Washington said. "He's such a valuable asset."
Cruz has already been on the disabled list twice this season, once for each hamstring. In his 77 games, Cruz has hit .320 with 16 home runs and 64 RBIs.
Harden was scheduled to pitch Tuesday night at Tampa, a start that had already been pushed back while Harden dealt with his shoulder.
Washington said after the Red Sox game that Tommy Hunter (9-1) will start Tuesday, a day earlier than he was scheduled to throw. Hunter pitched Friday night in the opener against Boston, but left after allowing three consecutive homers to start the fourth inning.
The Rangers said after Hunter was pulled Friday night that he had been dealing with a stomach bug. The big right-hander was told to stay home Saturday, but was feeling better Sunday.
Left-hander Derek Holland likely will be be recalled from Triple-A Oklahoma to start Wednesday night's game for Hunter.
Harden's DL move is retroactive to Aug. 8, the day after he walked five batters and gave up three runs in 2 1-3 innings in a loss at Oakland.
Harden signed a free-agent deal with Texas last winter for $6.5 million with a chance to earn another $2.5 million in performance bonuses. There is an $11.5 million mutual option for 2011 with a $1 million buyout for the Rangers.
With Cruz out of the lineup Sunday, struggling Vladimir Guerrero getting a day off and Josh Hamilton the designated hitter, rookie Mitch Moreland got his first start in right field after starting nine games at first base. Julio Borbon was in center and David Murphy in left.
Guerrero hit .196 (18 for 92) his last 24 games to fall from .325 to .297 overall. He had only four extra-base hits (one home run and three doubles) in his past 28 games.