The two RBI for Towles came one night after he had set a club record by driving in eight runs.
Houston won its third straight, with Brandon Backe (2-1) getting the victory. He allowed two runs on six hits over six innings.
St. Louis has lost five of its last six games and 14 out of 16. The Cardinals have been out-scored in their last five contests, 45-21.
Joel Pineiro (6-5) gave up three runs on eight hits in 5 2/3 to take the loss.