Norris, who is 5-4 with a 4.81 ERA in 13 starts, sprained his knee pitching against the Giants on Tuesday in San Francisco. He was scheduled to start Sunday against the Rangers, but the Astros called up left-hander Dallas Keuchel from Triple-A Oklahoma City to make his Major League debut.
"I'm frustrated," Norris said. "Nobody wants to go on the DL, but I know I need to get this thing right, because once I get it right I can pitch the way I was capable of pitching the first 10, 15 starts."
Norris, 27, injured his hip flexor May 31 against the Rockies and wasn't the same. He was 5-1 with a 3.34 ERA in his first 10 starts of the season but was 0-3 with a 13.09 ERA in his next three starts as he dealt with leg problems.
"I've been trying to go out there and pitch at 80 percent and unfortunately I haven't been helping the team much," Norris said. "It's frustrating in that regard. I want to be out there every fifth day, but I understand that short term is more important than the long term and I have a whole second half to put it together to come back from this thing. I'm hoping it doesn't take a long time."
Astros manager Brad Mills said he didn't want Norris to try to pitch through any discomfort.
"It's something that we want to make sure he's 100 percent when he comes back and that he's not tentative when he's putting weight on it," he said. "We'll get him back going as soon as we can and hopefully we can get him 100 percent."
This is the second career trip to the DL for Norris, who went on the shelf in 2010 with biceps tendinitis.
"You're going to through some things, some bumps and bruises, where you're going to have to go out there and pitch," Norris said. "I definitely gave it everything I had and it didn't go my way. I have to give my knee some time, the whole leg some time. I have 15 days to do it. I'm feeling a little bit better, and day in and day out I have to get treatment to get me back out on the field."