Robertson is on the 15-day disabled list with a strained left oblique, while Gardner is on the DL with a right elbow injury.
"Gardy did well in his stuff today," Girardi said. "Eventually we'll get him on the field, we'll get him hitting pretty soon, then we'll get him in some games."
Girardi said Gardner took some batting practice in the cage on Friday, and the Yankees are eyeing a possible return in a week or so.
"I think it's possible we could have him next weekend, or the series after that," Girardi said.
As for Robertson, it's more likely to be about two weeks, since his timetable for recovery is not as accelerated.
"You've got to get him a [batting practice] and got to get him in some games -- more than one game -- and the problem with a reliever is you can't go three days in a row or four days in a row, like a position player," Girardi said.