DENVER -- Todd Helton was happy about hitting his 300th home run. He was much more concerned with Colorado's playoff chances, though.
"I'm very proud of it. It's an honor to be able to go out and be on the field that long," Helton said. "But I mean, the situation we're in as a team right now is definitely the most important thing."
Matt Holliday and Garrett Atkins also homered in Colorado's 20-hit outburst. Helton got four hits for the fourth time this season, and Iannetta had a career-high four RBI.
Holliday matched his career high with four hits, helping the Rockies (77-72) end a three-game skid. They surpassed their win total from last year and stayed 4½ games behind San Diego in the NL wild-card race.
"Time is running out and we can't afford losses," Helton said. "We're going to have to catch some breaks and need to get some help."
Franklin Morales (2-2) allowed three hits in six innings for the victory. He struck out five and didn't walk a batter.
Morales and three relievers combined for Colorado's sixth shutout this season and first at Coors Field. The team's previous shutout at home came July 24, 2006, when Jeff Francis blanked St. Louis 7-0.
Florida had its season-high four-game winning streak snapped.
Atkins and Iannetta homered in the second to put Colorado ahead 4-0. Atkins hit his 23rd of the year leading off the inning, then Iannetta golfed a three-run shot into Florida's bullpen in right-center for his fourth home run this season.
"We haven't lost sight of anything," Colorado manager Clint Hurdle said. "Every day we show up it's important to win that day and that's the way it will continue."
Florida starter Scott Olsen (9-14) didn't retire a batter in the third. He gave up singles to Holliday, Helton and Atkins before walking Ryan Spilborghs to force in a run. Ross Wolf relieved and a run scored when first baseman Jason Wood dropped shortstop Hanley Ramirez's throw for an error that allowed Helton to score.
Olsen gave up six runs and eight hits in two-plus innings. He is winless in seven starts since Aug. 5.
"It wasn't a good day at all," Olsen said. "There have been a lot of these days this year."
Colorado extended its lead to 8-0 in the fourth on Holliday's two-run homer to left, his 32nd of the year. The ball hit a seat and caromed back onto the field, leaving umpires and Holliday unsure if it was a home run.
Holliday stood at third when third base umpire Chris Guccione ruled the ball in play, but Guccione changed the call to a home run after huddling with the other umpires.
Helton homered with Morales and Holliday aboard in the fifth to make it 11-0. Helton came out for a curtain call and tipped his cap. He has reached base via hit or walk in 18 consecutive games.
"It's just more fingerprints on a very elite position in the game, and one that you know you knock on wood and hopefully he'll end up in the Hall of Fame," Hurdle said. "He's been doing it for so long, has done some remarkable milestones."
Morales had faced the minimum through five innings when rain halted play for 30 minutes. After the delay, Matt Treanor and Brett Carroll singled to start the sixth, but Morales retired the next three batters.
"I don't know what we can do about Olsen," Florida manager Fredi Gonzalez said. "He makes good pitches to get to 0-2 and lets a slider up out over the plate and gets hurt."
- LF Josh Willingham was out of Florida's starting lineup with a sore back.
- Olsen had a one-inning outing on July 6 against Colorado in Miami.
- Marlins 3B Miguel Cabrera has an 11-game hitting streak.
- Colorado OF Brad Hawpe, batting .177 against left-handers, was not in the starting lineup.