Howard's fifth-inning grand slam tied Schmidt for the most in team history with seven. Howard already two grand slams this year.
Joe Blanton (1-2) gave up one run on four hits in six innings.
Jayson Werth had a two-run homer for the Phillies, who have won seven of their last nine games.
Former Phillie Kyle Lohse (3-1) suffered his first loss of the season, giving up six runs on seven hits in 4 1/3 innings.
Joe Thurston, another former Phillie, was 3-for-5.