The game was tied 8-8 after one quarter before the Tigers reeled off 46 unanswered points to build a 54-8 lead. Harding got a safety in the fourth quarter to end the scoring.
Gravitte ran for three touchdowns and took a swing pass from Ryan Dunn 70 yards for another score.
Rowe, who started at quarterback, ran for two more touchdowns, and Will Bonaparte and Jack Boscia added short TD runs.
Ridgefield, which was coming off a loss to McMahon, raised its record to 6-2.
Harding dropped to 0-8 with the loss.