The Brewers scored twice in the eighth with the help of four of Colorado's five errors.
Herrera, a leading candidate to make the Brewers as a utility infielder, has four hits in seven at-bats this spring with three RBIs while playing well at shortstop.
"I got just enough. As long as it gets out, that's enough," Herrera said of his homer.
Wheeler had an RBI single while Tom Murphy and Kyle Parker had run-scoring doubles for the Rockies.
Rockies manager Walt Weiss questioned a call on a stolen base by Milwaukee's Logan Shafer in the sixth. Shafer was ruled safe by second base umpire Jim Wolf and after a replay review of less than two minutes, the ruling on the field was upheld.
Weiss lost the review but was happy with the process.
"I like it. I like the concept and the fact that we're trying to get it right," Weiss said. "It's not going to be perfect right away. It's being implemented on a large scale. But I like knowing that you have the ability to overturn a call. I thought he might have tagged him."
Rockies: Jordan Lyles is completing for the final spot in the rotation and Thursday's effort will help. He allowed three hits in three scoreless innings, striking out Richie Weeks swinging and Reynolds looking during his stint.
"I saw him focusing on keeping the ball down," Weiss said. "I thought it was a very encouraging outing by him."
Brewers: Kyle Lohse gave up his first runs of the spring on an RBI single to Wheeler and an RBI double to Murphy in the second inning. But he rebounded to set the Rockies down in order in the third.
"I wasn't as good out of the stretch. It was a simple, mechanical thing that I forgot about," Lohse said. "If you're going to forget something simple in your mechanics, now is the time to do it."
HOT CORNER, HOT INNING
Colorado third baseman Charlie Culberson had himself a real fine second inning.
He singled, stole second and scored on Wheeler's single in the top half. In the bottom half, he made a nice, backhand stab of Lyle Overbay's line drive and beat Carlos Gomez back to complete and unassisted, inning-ending double play.
RAINY DAY MAN
It's been mostly sunshine for the Cactus League, but Arizona had a storm blow through last Saturday and the area was under cloud cover again on Thursday. Lohse wasn't surprised he had the starting assignment each time.
"I'm just that guy. It goes back four or five years and I don't know what it is," he said. "One year in St. Louis I made 32 starts one year and in half of them, we had raindrops at least some part of the day. We had delays hold up my starts when I'm feeling good ... it just follows me around."
ONE MORE TIME
Weiss said it will be nice to see former Colorado closer Rafael Bentancourt, now a free agent and on the comeback trail from right elbow ligament surgery, this weekend. Bentancourt will arrive at the Rockies' camp Sunday for some supervised throwing for the training staff.
"It will be good to see Raffy," Weiss said. "He's meant so much to this club the last couple of years, his leadership. It will be good to have him around."
The 38-year-old is hoping to pitch this season, and his rehab process could have him ready by August.