Harper connected in the fifth inning for his second homer this spring. He is batting .462 in exhibition play.
Zimmerman followed with his first home run, tagging reliever Brad Hand.
Zach Walters hit his second spring homer in the eighth for the Nationals.
Joe Mahoney hit a two-run homer for Miami.
Washington's Chris Young struggled in his first spring allowing three runs in three innings while also walking three. Miami starter Alex Sanabia lasted 2 2-3 innings, giving up four runs and five hits.