Blum's hit off Burke Badenhop (0-2) that Cameron Maybin had to chase almost to the wall in center field, gave the Astros their fourth straight win and fifth in the last six games after an 0-8 start.
It was the second night in a row that a player came off the bench to help win the game after Jason Michaels hit a homer in the eighth inning of Houston's 7-5 win Tuesday in Berkman's first game of the season.
"I think they did a good job of keeping a good nucleus on the bench with myself, Michaels and (Jeff) Keppinger," Blum said. "I think it's going to be a pretty good mix for us in the long run."
Still, the Astros believe the return of Berkman has given the them a boost of confidence.
"We got Lance back and just his presence, he's going to deliver and you know he's going to hit, you know he's going to make plays in the field and just give us some more depth in the lineup," Michael Bourn said.
Humberto Quintero had two hits, including a homer, for the Astros to send the Marlins to their first series defeat of the season.
Wilton Lopez (1-0) allowed one hit and no runs in two innings for the win and Matt Lindstrom pitched a scoreless ninth for his fourth save.
Houston had consecutive singles by Pedro Feliz and Kaz Matsui in the seventh inning before Blum's two-RBI triple with one out gave Houston a 5-4 lead. The hit completed a comeback for the Astros who trailed 4-1 after Florida's four-run fifth inning.
Badenhop allowed three hits and two runs with two strikeouts in the seventh before Christopher Leroux pitched a scoreless eighth.
Bourn doubled in the sixth inning before a walk by Keppinger. Berkman reached on a fielder's choice and Keppinger was out at second, leaving Bourn stuck between second and third. Hanley Ramirez got an error after crashing into Bourn after the fourth throw of the run down, allowing him to reach third.
"I was just really concentrating on getting the ball out of my glove on that play," Ramirez said. "I was standing on the line, and I could not get out of the way."
Carlos Lee -- who has had at least 100 RBIs in each of the last five seasons -- drove in his first run of the year on a single to left field in the sixth to get Houston within 4-3. The Astros' second out of the inning came when Berkman was caught trying to steal third. Before the game, he talked about his concern about sliding for the first time since knee surgery and looked more than a bit rusty when he did.
Berkman said Houston's streak doesn't surprise him.
"People wrote us off early and I think we have a good team," he said. "I look at the pitching staff and the guys that we have and to me it's a good ball team."
Marlins starter Josh Johnson retired Pence to end that inning.
Johnson allowed a single by Quintero with no outs in the third inning before retiring the next eight batters. Then it was Quintero again, this time with a solo homer to center with two outs in the fifth that made it 4-2.
Johnson allowed four hits and two earned runs in six innings.
Astros starter Bud Norris didn't allow a hit until Dan Uggla's single to start the fifth. He walked John Baker before striking out Cody Ross. A single by Gaby Sanchez scored Uggla to tie it 1 before Baker scored on a sacrifice bunt by Johnson. Maybin pushed the lead to 3-1 with his run-scoring triple that fell just behind a sprinting Bourn in center field.
Keppinger overthrew first base to allow Chris Coghlan to reach and Maybin to score and make it 4-1. Norris finally got out of that inning when Bourn raced up the hill in center field to grab a high fly ball from Ramirez.
Norris left after giving up three hits and four runs with five strikeouts in five innings.
Marlins manager Fredi Gonzalez isn't worried after his team dropped its first series.
"No," he said. "You want to win games, and series. You want to win every game. I don't care if it is in April or September. But nobody is panicking right now. This was a good ball game."