Lohse stretched his career-best winning streak to eight games and upped his record to 11-2, hurling seven scoreless innings and allowing six hits.
Coming into the game, Lohse said he didn't feel good warming up in the bullpen.
"It was one of those warmups where you kind of figure out a way to get out there and get it done, and that's basically what I was able to do," said Lohse.
As the game wore on, Lohse got better and better.
"The sinker was working -- I was throwing a good sinker," Lohse said. "I was just trying to worry about keeping it on the corners, but the main objective was keep it down in the zone, and that's what I was able to do."
The start was just what the doctor ordered for the Redbirds.
"I thought he was excellent," Cardinals manager Tony La Russa explained. "He got a little sloppy that one inning and pulled it together before anybody could score. It was just another consistently outstanding performance."
Pirates manager John Russell said that Lohse was the difference in the game.
"He threw the ball well," Russell said. "We had a couple of chances earlier in the game to get him and he made good pitches to get out of it. He was pretty efficient. He changed speeds real well. His slider was working real well for him and he used it very effectively. He settled in and threw a really good game against us."
Pirates starter Zach Duke absorbed the loss, falling to 4-6 on the season. He was tagged for five runs on 10 hits.
The Cardinals jumped on Duke for four runs in the top of the third inning. Yadier Molina stroked a two-run double, plating Albert Pujols and Troy Glaus, who had singled. Rick Ankiel then crushed his 20th home run of the season, staking the Cards to a 4-0 lead.
Lohse appreciated the run support.
"It's huge," Lohse said. "I thought early on that Duke was doing a really good job and we were going to be in for a battle, and when we put those four up, it kind of takes a little stress off and you can go out there and have that cushion and just stay away from the big inning."
St. Louis did all its damage in the third with two outs, thanks in part to Ankiel's timely home run.
"It's a good time and I think baseball is a long year," Ankiel said. "I think you are going to go through stretches where you get two-out knocks and you are going to go through stretches where you're not. It seems like that's the way it is."
In the top of the fourth inning, Ryan Ludwick smacked the first offering from Duke into the left-field stands for his 19th home run, giving St. Louis a 5-0 advantage.
Ankiel upped the Cards' lead to 6-0 with a seventh-inning RBI single off Pirates reliever Denny Bautista.
Rookie right-hander Jaime Garcia made his first Major League appearance, tossing two scoreless frames to close it out for the Cardinals.
"The first inning, I didn't feel anything," Garcia said. "I just went in there and tried to do my best, and in the second inning, I started thinking too much and realized it was my first big league game and I got a little shaky and nervous. But after that, you just try to throw strikes, and we were winning by six, so you just try to throw strikes."
George Von Benko is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.