Lagergren (66) had eight birdies and two bogeys for a 6 under in the second round. Stalter (68) soon joined him for a share of the lead. Both are bidding for their first European Tour title.
''Playing really, really good, especially from tee-to-green,'' Lagergren said. ''So I'm happy with that.''
Garcia (70) was on course for the lead but bogeys on the 14th and 17th set the Masters champion back before he finished with his fourth birdie.
''I would have loved it to be 4 or 5 under, which I think I could have done quite easily, but, you know, it was a little bit tricky out there today,'' Garcia said of the windy conditions on the Eichenried course.
Garcia is playing his first event in Europe since his Masters win.
Stenson, the defending champion, went one better with a 69 as he joined Garcia, Richard Bland, Rikard Karlberg andThomas Detry at 8-under.
''I'm not on top of my game by any means but I think it was a good kind of professional fighting display,'' Stenson said.
Martin Kaymer failed to make the cut with a second straight 72.
''I fought to the end, created many chances,'' said Kaymer, the 2008 champion. ''But it wasn't to be.''