Blackmon finished 6 for 6 with three doubles and a two-run homer. The only other Rockies player with six hits in a game was Andres Galarraga against Houston on July 3, 1995.
Carlos Gonzalez added a two-run triple and a two-run homer off the facing of the third deck as the Rockies improved to 13-9 in home openers.
The Diamondbacks fell to 1-6, their worst start since 1998.
Randall Delgado (0-1) gave up six runs and 10 hits in four innings.