Jordan Zimmermann (6-6) pitched six scoreless innings allowing four hits and striking out six for the Nationals, who have won six of eight.
Josh Johnson (5-6) lost to Washington for the first time in his career as he allowed five runs and 11 hits in 5 1/3 innings. Johnson was 8-0 in 15 starts against the Nationals.
The Marlins were out-hit 13-7 and have dropped three straight.
Ian Desmond’s RBI single scored the Nationals’ first run before Zimmerman connected to left-center field in the third to make it 3-0.
Zimmermann allowed three hits to the first five batters before settling down. He was at his best in the fourth inning when he struck out Logan Morrison, Hanley Ramirez and Justin Ruggiano, all swinging.
Adam LaRoche singled to lead off the sixth, his third hit of the game, and Desmond followed with a hit. Flores drove them both home with a single to left that dropped right in front of Morrison. LaRoche crossed home plate just before Desmond, who was only three steps behind and extended the lead to 5-0.
Flores’ hit ended Johnson’s outing.
The Marlins threatened in the seventh when Zimmermann left in favor of Henry Rodriguez. After John Buck’s RBI single scored Ruggiano to make it 5-1, Austin Kearns lined into an inning-ending double play to pitcher Michael Gonzalez, who relieved had Rodriguez.
Ruggiano stole a career-high three bases.
NOTES: Zimmerman’s home run was his 15th against the Marlins, the most he’s hit against any club. ... Ramirez was dropped to fifth in the lineup for the first time in his career after closing the first half on a 2-for-22 slump. “Hanley is struggling at the plate,” manager Ozzie Guillen said. “As Hanley starts hitting better he will be moved back to where he is supposed to be (in the third spot).” ... Miami placed OF Giancarlo Stanton (right knee surgery) on the 15-day DL, retroactive to July 8, and activated OF Emilio Bonifacio (left thumb surgery) off the 15-day DL after Bonifacio missed 46 games. Stanton is expected to miss 4-6 weeks. “I don’t know (when I’ll be back), I just started walking,” Stanton said. “I honestly have no idea. They say four to six weeks, but I’ve got no clue.” ... Marlins first-round pick LHP Andrew Heaney signed a $2.6 million bonus just before Friday’s deadline and was in attendance. ... Miami-native LHP Gio Gonzalez (12-3, 2.92 ERA) will start Saturday for the Nationals against LHP Mark Buehrle (8-8, 3.25 ERA), who has won his last three starts.