Asche, one of the team's top prospects, was hitting .295 with 15 homers and 68 RBIs in 104 games at Triple-A Lehigh Valley. The move was announced before struggling Philadelphia opened a nine-game homestand Tuesday night.
Outfielder Steve Susdorf was designated for assignment to make room for Asche.
The Phillies have lost eight straight games to fall out of contention. Asche's arrival could pave the way for Michael Young's departure if the veteran waives his no-trade clause.
