"I just worked on some stuff in between starts and felt good about the adjustments I made," Vogelsong said. "I have to focus on mechanics and let the ball do what it wants to do. It feels like before I was trying to force the ball to places instead of just letting it work."
The Giants threw their third shutout in a row and second against the Padres, who came to town after scoring 26 runs in a three-game sweep of Colorado last weekend.
San Diego has gone 20 innings without scoring.
"Guys are throwing the ball well," Giants manager Bruce Bochy said. "It's good to see these guys get locked in. It's a talented staff and we're seeing who they are and how they can pitch."
Brandon Crawford had three hits and an RBI for the Giants, who won their eighth straight at home and are a game over .500 (14-13) for the first time since April 10, the beginning of an eight-game losing streak. Justin Maxwell and Matt Duffy, who had two hits, also drove in runs.
Vogelsong (1-2) walked two and struck out four in his longest outing of the season. He retired 11 of his first 12 hitters and pitched out of a bases-loaded jam in the sixth.
George Kontos and Yusmeiro Petit each worked an inning to complete the four-hitter.
Andrew Cashner (1-5) remained winless in eight games, four starts, in San Francisco. He gave up six runs — four earned — and seven hits over six innings. He walked three and struck out three.
"A little bit of a rough night for Cashner," Padres manager Bud Black said. "Fastball command wasn't there for him. He left some balls out over the plate and couldn't really gain any momentum. He had a good first inning and from there it seemed to unravel."
Padres: RHP Brandon Morrow went on the disabled list with right shoulder inflammation. "I'm not injured," he said. "It's just recovering less and less each week, and the thinking is, miss two starts now and save missing five or six in the future." LHP Frank Garces, who opened the season with the Padres, was recalled from Triple-A El Paso. RHP Odrisamer Despaigne replaces Morrow in the rotation and will start Thursday night at Arizona.
Giants: OF Angel Pagan was scratched from the lineup with a cut on his middle finger. The injury occurred Monday night when Pagan stole second and his finger was stepped on. ... RHP Jake Peavy (strained lower back) threw a bullpen session and came out of it OK. "We haven't decided what the next move is for him," Bochy said. ... OF Hunter Pence (broken left hand) will get a day off from taking batting practice on the field after an active session Tuesday.
Padres: RHP Ian Kennedy (1-1, 7.11 ERA) will make his first road start of the season Wednesday in the series finale. He's 9-4 with a 2.48 ERA in 22 starts against the Giants. 1B Brandon Belt is hitting .320 against Kennedy with two home runs, but has struck out 10 times.
Giants: RHP Chris Heston (2-2, 2.51) made his first major league start against the Padres last September.