Plouffe, who had been batting seventh, moved up ahead of Ryan Doumit and hit sixth on Sunday.
"We wanted to put a lefty behind him and see what happens," Gardenhire said. "He didn't get anything yesterday."
Plouffe has been one of baseball's hottest hitters, as he leads the Majors with nine homers and a 1.465 OPS in June.
Gardenhire, though, said he's fine with Plouffe drawing walks if he's not getting pitches to hit, as it's better than chasing pitches he can't drive.
"That's the key -- you can get too aggressive there and try to do too much," Gardenhire said. "But he took his walks. And that's a good thing."