Dodgers starter Hiroki Kuroda (5-1) limited the slumping Astros to three runs on seven hits.
A trio of relievers each turned in scoreless 1-inning stints after Kuroda was lifted for pinch-hitter Garret Anderson.
Carlos Lee homered and drove in all three runs for the Astros, who have lost five straight. Bud Norris (2-5) took the loss after giving up six runs on seven hits.
Lee's RBI single in the third inning tied the game but Los Angeles struck back with a run in the fourth and two in the fifth on Ramirez's two-run single.
Blake closed out the scoring in the eighth with a solo home run.