Flowers’ drive just inside the foul pole in left field was the third straight hit after Grimm (2-1) retired 10 in a row on the day he was named AL rookie of the month.
The Virginia High alum, who had a 1.59 ERA in three April starts to earn rookie of the month honors, was cruising with two outs in the sixth when Conor Gillaspie and Alexei Ramirez singled before Flowers hit his fourth homer of the season.
After walking three in the first 2 1-3 innings, Grimm didn’t give up another free pass and tied his career high of nine strikeouts set last month against Seattle. He allowed six hits in 6 2-3 innings.
“He really had good stuff working tonight,” Rangers manager Ron Washington said. “Just left one in the wrong spot to Flowers.”
Hector Santiago (1-1) allowed two hits in five-plus innings filling in for Jake Peavy, who was scratched with back spasms.