Pujols' third-inning homer off starter Jason Jennings was the slugger's first hit of the series and it shook him out of a 1-for-17 skid.
"Sometimes you see the ball well," Pujols said. "You need to make adjustments and I try to make an adjustment every at-bat. That's what I did today -- tried to figure out how they were pitching me and hopefully adjust to those things."
Rolen came into the game with only two hits in his first 17 at-bats this season. He had an RBI single in the eighth inning and a three-run double in the ninth off closer Brad Lidge.
"You can't get confidence without success," Rolen said. "I certainly feel better leaving Houston."
The Cardinals finished with 13 hits after mustering 29 in their first five games.
"We needed to get going," Pujols said, "and obviously, that's what we did today. Everybody contributed. That's what our goal is."
As the St. Louis offense broke loose, starter Kip Wells shut down the Astros and outpitched Jennings, his former college teammate at Baylor.
Wells (1-1), a Houston native, allowed one hit and struck out seven in seven scoreless innings. He retired the last 16 batters he faced after hitting Chris Burke with a pitch in the second.
The more Wells relaxed, the better he felt on the mound.
"The first couple of innings, I was putting a lot more effort into the pitches than I did as the game progressed," Wells said. "As I backed off a little bit, that gave me a little better command and a little better finesse. For me, that's something I constantly need to be aware of -- not trying too hard."
Jennings (0-1) gave up five hits, including Pujols' homer, and struck out five in five innings. He got no support from the Astros' offense, which managed two runs or less for the fourth time in six games.
"Jennings threw a pretty decent ballgame," Astros manager Phil Garner said. "He deserved better."
Houston finished with three hits and fell to 1-5, matching its worst start since 1990.
"We looked like we hadn't had any spring training today," Garner said. "We did not take good at-bats at all."
The right-hander's first pitch to Wells skipped away from catcher Brad Ausmus, and Edmonds sprinted home to put St. Louis up 1-0.
Jennings walked Chris Duncan with one out in the third and Pujols followed with his first homer of the season, a 410-foot shot off the railing in left-center. It was Pujols' first hit in 14 at-bats.
Wells gave up only Mark Loretta's bloop single in the second. He needed 90 pitches to blank the Astros through seven innings.
"For me, it's not overthrowing, it's staying within myself and using the strike zone to my advantage," Wells said. "It's getting into a rhythm and staying there. I got some quick outs, some quick innings and those give you a chance to pitch deep into games."
Duncan, Pujols and Rolen opened the eighth with singles off reliever Brian Moehler to extend St. Louis' lead to 4-0. The 35-year-old Moehler signed with the Astros as a free agent in January.
Lidge came in for the ninth and the Cardinals loaded the bases with one out. Rolen then brought everyone home with a line drive off the left-field wall.
Lidge has given up six runs in two brief relief appearances this season.
Luke Scott drove in the Astros' only run with a double in the ninth.
"Clearly, our lineup is not clicking," Garner said. "We're not getting on, we're not getting any movement. It wasn't a very good day offensively."
- Pujols homered for the fourth time the past two Easters. Last April 16, he hit three homers, including the game-winner in an 8-7 victory over Cincinnati.
- Pujols has 17 homers at Minute Maid Park, the most by an opposing player in the ballpark's eight-year history.
- The Astros play 14 of their next 16 games on the road.