Garland (3-2) allowed only three hits, walked five and struck out three. Mike Adams hurled a perfect eighth and Sean Gallagher preserved the shutout with a scoreless ninth as the Padres won at home for the ninth time in 10 games.
Hairston added a single, Tony Gwynn tripled home a run and Kyle Blanks added a solo shot for San Diego.
Milwaukee starter Randy Wolf (2-2) lasted only five innings, giving up four runs on six hits.
The Brewers, who have dropped eight of their last 10 games, were shut out three times in the weekend series.