Wandy Rodriguez will be Houston's first left-handed pitcher in 38 years to start on opening day when he faces the Colorado Rockies on April 6.
Manager Brad Mills announced the starter Wednesday, a day after the 33-year Rodriguez pitched six innings against the Detroit Tigers.
Rodriguez has been with the Astros since 2005, longer than any other player. He's started 197 games, but none on opening day. He was 11-11 last year with a 3.49 ERA on a team that lost 106 games.
Rodriguez is 2-2 with a 7.88 ERA in four starts this spring.
The Astros sent four players to their minor league camp, including infielders Angel Sanchez and Brian Bixler and released infielder Joe Thurston. Infielder Scott Moore was reassigned and pitcher Enerio Del Rosario was optioned to Oklahoma City.