The 27-year-old was out of the lineup for the 12th straight game on Tuesday with left Achilles tendinitis. The former All-Star was scheduled to return to the field as a designated hitter in a minor league game Tuesday afternoon.
"It's the right thing to do physically and also with regard to his preparedness," Phillies general manager Ruben Amaro Jr. said Tuesday. "We want to make sure he's playing well and getting his legs underneath him and swinging the bat, doing the things he needs to do to get ready for the season to help us in Philadelphia."
Brown was placed on the DL retroactive to March 27. He will be eligible to be activated April 11.
"We'll take him at the appropriate pace," Amaro said.
Amaro said Brown will serve as a designated hitter Tuesday in a minor league spring game. The Phillies are bracing for the possibility that the 27-year-old could miss more than the opening week of the season.
"It could be more than that [opening week]. It very likely could be more than that," Amaro said. "We're going to take it at the appropriate pace to make sure that it's not a lingering issue for him during the year."
Brown, the Phillies regular left fielder for the last two seasons, was slated to start the season in right field, the position he played when he originally broke into the big leagues in 2010. A first-time All-Star in 2013, Brown struggled throughout the 2014 season: he hit .235 with 10 home runs in 144 games.
In 2013, Brown's first full season in the big leagues, he hit .272 with 27 home runs. Only three National League players hit more home runs that season.
Brown hit .241 with one double in 11 games this spring training.
The Associated Press contributed to this report.