The Rockies ran their winning streak to six games in a contest played in temperatures that struggled to climb above freezing.
Colorado took a 3-2 lead into the seventh and then broke the game open by sending 11 men to the plate.
Carlos Gonzalez had three of Colorado's 17 hits, which were produced against five New York pitchers.
Jon Garland (2-0) picked up the win by limiting the Mets to two runs on six hits in seven innings. He struck out four and did not walk a batter.
Jonathon Niese (2-1) suffered the loss while giving up three runs in six innings, but it was reliever Josh Edgin who was touched for the big inning.
Edgin loaded the bases with two away before Rosario delivered a two-run single. Helton followed with a two-run double.