He has a few options, including two candidates -- Jason Lane and Luke Scott -- who have made cases for themselves this spring, while Richard Hidalgo is still lagging behind.
Garner could decide to give the majority of the starts to one, or he could platoon Lane and Scott, starting left-handed-hitting Scott against right-handed pitchers and vice versa for the right-handed-hitting Lane.
Garner isn't leaning toward the platoon plan, but is keeping his options -- and his mind -- open.
"There are advantages to it," Garner said of the platoon. "I don't know about [Hidalgo] so much, but I do know most recently about Jason and Luke. Either one of them, if they're hot, it doesn't matter if it's [against righties or lefties], they both hit them well.
"Jason, if he's swinging the bat well, he'll hit right-handers. Luke, if he's swinging the bat well, he crushes left-handers. It's not that there is a glaring weakness there. It's a way to get both guys in the field a little bit."
Lane began Spring Training considered by some to be behind Scott on the right-field depth chart, but after an offseason of rigorous flexibility training and a determination to erase from his memory his disappointing performance in 2006, he rebounded this spring to post a .271 average through Friday's game.
"Anytime you're flexible and strong in your legs, you have a stronger foundation, you have a lot more confidence," Lane said. "I feel like last year, there were a lot of balls that I hit pretty good that ended up at the warning track, that with more strength may have had a little extra carry and I'd end up driving the ball a little more."
About last night ... The Astros' 16-2 loss to the Nationals on Thursday night was undeniably ugly, as were the performances by two rotation hopefuls, Brian Moehler and Chris Sampson.
Garner will reserve judgement on the two pitchers until after their next starts, which should happen later next week.
"You wait," Garner said. "Some guys may have a rotton outing and bounce back from it and pitch very well. You can have a little bit of a dead arm. I don't know if that had anything to do with anything -- neither one of them have used it as an excuse. It's feasible you can have a bad outing during Spring Training and not be as sharp as you would be otherwise."
That said, the Astros are in the stretch run of the exhibition season. If those in the running for the fourth- and fifth-starter jobs are planning to leave any kind of indelible impression, they've got about a week to do so.
"It's unfortunate that if you're battling for a job, these few outings will be what determines who might break with the ballclub," Garner said. "That doesn't say that's who stays with the ballclub. It can determine who breaks. That's all we have to go on. Past history does have something to do with it. Guys that have done a job for us get the leg up on that."
Fine-tuning: One Astro who most definitely does not have to worry about winning a job is ace right-hander Roy Oswalt, who channeled his Spring Training boredom into a very effective start against the Indians on Friday.
Oswalt threw six shutout frames, allowing three hits and two walks while striking out five. He said he was a "little erratic" in the first two innings and admitted his curveball wasn't working until the third frame.
"I was a little wild," Oswalt said. "I was in the strike zone, but I was falling open too much. When I line up on the rubber, I always land a little bit closer toward third or even straight toward the plate. Today, I was landing on the first baseman's side of the plate, just a little too far open."
Oswalt's next start is scheduled for Wednesday in Tampa against the Yankees, but he may throw in a Minor League game instead.
"We're looking at doing that," Garner said. "But we'll firm that up [Saturday]."
Ensberg on the mend: Garner had not scheduled Morgan Ensberg to travel with the team to Winter Haven on Friday and reiterated that the third baseman's rather rough game the night before had nothing to do with the extra day of rest.
Ensberg took a batted ball off his leg and was later hit by a pitch in the rib cage area during the Astros' game with the Nationals, and as a result, was lifted after just two innings.
Garner does not expect the bumps and bruises to force Ensberg from the lineup Saturday.
"He has a bruise where that ball hit him on the knee," Garner said. "He's fine. He'll play tomorrow. He was not scheduled to make this trip anyway."
Odds and ends: Left-hander Scott Sauerbeck accepted his Minor League assignment and will report to Minor League camp Saturday morning. Sauerbeck, a non-roster invitee, was reassigned on Monday, but had the option to ask for his release. ... Five players from Minor League camp accompanied the Astros to Winter Haven: right-hander Jose Rodriguez, left-hander Philip Barzilla, catcher Kevin Davidson and infielders Edwin Maysonet and Wade Robinson. ... Jason Jennings will face the Tigers at Osceola County Stadium on Saturday. Projected No. 4 starter Wandy Rodriguez will face the Mets in Port St. Lucie on Sunday, with Woody Williams making a home start against the Braves on Monday. ... Jennings will likely start the Astros' exhibition game in Round Rock on March 29.
Up next: After three consecutive night games, the Astros will host the Tigers for an afternoon matchup Saturday at 12:05 p.m. CT. Jennings will take the mound for Houston.
Alyson Footer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.