J.B. Shuck drove in a pair of runs and Wandy 0, in the first of three between the clubs.
Carlos Corporan collected three hits, scored twice and knocked in a run for the Astros, who have won three in a row. Brian Bogusevic homered and scored twice.
Rodriguez (9-9) scattered five hits and walked two, but fanned eight and added a two-run single for the victory.
Ryan Vogelsong (10-3) allowed four hits and five runs -- only two earned -- over seven full frames in defeat as the Giants lost for the fourth time in five games.