Cashner, sidelined with a strained right rotator cuff, and Wells, out with a strained right forearm, both went on the disabled list April 6.
"I don't think either one is very happy about [leaving the team], and that's OK, too," Cubs manager Mike Quade said Wednesday.
They both had side sessions on Wednesday at Dodger Stadium. The plan is for both to have two more side sessions in Arizona and, if all goes well, face hitters in batting practice.
They're going to Arizona to take advantage of the nice weather.
"If there's ever a place to get a lot of work done rehabbing, Arizona is the place," Quade said. "Hopefully, the next time I see him they'll be on the verge [of returning]."