After Jesus Guzman led off the seventh by being hit by a pitch, Rico Noel pinch-ran and stole second before Gregorio Petit drove him home with a single. Petit advanced to third on an error before Blanks' fly to center made it 3-2.
Jonathan Galvez delivered an insurance run with a double, scoring Yasmani Grandal, who reached on a pinch-hit single.
But the Rangers made it 4-3 in the eighth on a two-out, RBI single by Aaron Cunningham, then won it with two runs in the ninth.
Joey Butler reached on an infield single with one out, scoring Jim Adduci from third with the tying run. Jeff Baker then singled to right with two outs, scoring Julio Borbon with the winning run.
Padres left-hander Eric Stults, one of several candidates for a rotation spot, got off to a rocky start but managed to settle down and pitch three solid innings, surrendering two runs on two hits.
"The second time out, it was a little easier," said Stults, who struggled in his debut last week. "The first time facing hitters, game speed, I was maybe a little too amped up."
The Rangers opened the scoring when David Murphy's two-out single plated Ian Kinsler and Beltre. Batting leadoff to get extra at-bats in, Beltre (right calf injury) went 1-for-3, reaching second base in the third on an error. He showed no ill effects of the injury while running the bases or playing in the field.
The Padres were held hitless through three innings by Rangers ace Yu Darvish, who threw 23 of his 39 pitches for strikes. They broke through with two hits in the fourth off reliever Neal Cotts -- one of them a double by Guzman -- but couldn't get a run across in the frame.
An inning later, Blanks crushed a 3-1 Cotts offering into the Bermuda grass in left-center field, cutting San Diego's deficit to 2-1.
A.J. Pierzynski doubled in the fourth, as he continued his solid spring.
Up next for the Padres: The Padres return to Peoria, on Tuesday for a 12:05 p.m. PT game against the Dodgers. This will be the first meeting of the spring between the two NL West teams. Jason Marquis, who tossed two scoreless innings his first time out, is scheduled to start and go three innings. Marquis is working on adding a changeup, a pitch he's gotten pointers on from former Padres closer Trevor Hoffman. Tyson Ross is also scheduled to pitch Tuesday. He'll follow Marquis and will also likely go three innings. Ross has allowed five earned runs in his first five innings this spring.