Francisco finished with three hits, three runs scored and three runs batted in, while Mike Sweeney and John Mayberry also went deep for the Phillies, who have won 19 of their last 23 road games and each of their last eight road series.
"It's good to get some ABs here in the last few days," Francisco said. "I think all of us are pretty excited to get in there. I mean, we've been sitting for a while. So it's pretty good to get out there and contribute."
Blanton (9-6) yielded a lone unearned run on only three hits while walking three and striking out six for the Phillies, who finished the month with a 21-6 mark and fell one win shy of matching the club record for wins in September.
Ross Detwiler (1-3) was saddled with the loss after allowing all seven runs on seven hits, including all four long balls, and a pair of walks while fanning two for the Nationals, who finished their last homestand of the season at 6-4 to end their 2010 home slate with a 41-40 record.
"Our players appreciate the way the fans treat them here," said Nationals manager Jim Riggleman. "So it's going to get the reputation of a great place to play, but you can only wait so long. Fans have been very patient, and hopefully in the near future we'll get this thing really going in the right direction."
Sweeney and Francisco started the second inning with back-to-back homers to left field to give the Phillies the early lead.
In the fourth, Sweeney walked and Francisco followed with a single before Mayberry walloped a three-run homer to left-center to give the visitors a five-run cushion.
Francisco's second long ball of the night, a two-run shot with two outs in the fifth, made it 7-1 and chased Detwiler from the game.
The hosts put two runners on with one out in the sixth before Blanton got Desmond to fly out and fanned Adam Dunn to end the inning.
The Nats threatened again in the seventh as the first two hitters reached. Blanton was then able to get a fly out, a pop up and a strikeout to keep the runners planted and end the frame and his outing.
The Phillies won 22 games in September of 1916 and 1983...Philadelphia is 10-1 in Blanton's last 11 starts and he is 5-0 in that stretch...Blanton has given up two earned runs or less in nine of his last 13 turns...He beat the Nats for the first time in three starts this year and evened his career mark versus the Nationals at 3-3...Blanton also squared his road record at 4-4 this year. Francisco had his fourth career multi-homer game and first with the Phils, who won the season series, 12-6...Philadelphia is 30-9 in its last 39 meetings with the Nats...The Phillies have won seven of their last nine series in the nation's capital...Philadelphia has also won 27 of its last 35 games within the division...Phils third baseman Placido Polanco had a cortisone shot in his left elbow Wednesday and is expected to rejoin the team over the weekend for the final series of the year in Atlanta...Detwiler is 0-3 in five games, four starts, against the Phillies.