San Francisco finished off a three-game sweep, getting a solid seven-inning start from Matt Cain.
The Giants have won four straight series.
Cain (2-1) did not allow a run through six innings and wound up surrendering two runs on four hits with six strikeouts in seven-plus frames. Florida scored a run in the ninth and had a runner on base before Brian Wilson came on to record the final out and pick up his sixth save.
Rowand finished off a three-run seventh with a two-run single. DeRosa had an RBI double in the second and a run-scoring single in the seventh.
The loss went to Ricky Nolasco (2-2), who gave up three runs on five hits in six innings.