Joachim Loew's side took a sizeable step towards claiming the single guaranteed place at South Africa 2010 from Group Four with three more points against a spirited Welsh side in their final qualifier of the year.
The result was a bitter pillow to swallow for John Toshack's team who defended passionately, but the Germany attack finally unpicked the lock on the Welsh goal when Trochowski rifled his shot home on 72 minutes.
Loew said before the game he expected Wales to bring a robust defence to Monchengladbach and that is exactly what Toshack's side provided.
Bayern midfielder Bastian Schweinsteiger had the best chance of the first-half when his shot beat Welsh goalkeeper Wayne Hennessey, but clipped the crossbar just after half an hour.
And Chelsea star and Germany captain Michael Ballack, who showed no signs of the damaged calf he suffered last Saturday in the 2-1 win over Russia, had an opportunity shortly after when his low-shot was also stopped.
West Ham striker Craig Bellamy had the best chance for the visitors, when on a rare Welsh forage into German territory, the Wales captain swung in a shot, but Germany goalkeeper Rene Adler covered the danger.
There was a surprise at half-time as 87-times capped striker Miroslav Klose, top scorer at the last FIFA World Cup finals, was substituted for Bayer Leverkusen's Patrick Helmes to make just his ninth appearance.
The Welsh had the brightest chance early in the half when Wolverhampton Wanderer's David Edwards flicked a ball into Bellamy's path who went one-to-one with Adler, but the goalkeeper stood tall and blocked the chance.
As the rain poured down, Trochowski wasted a golden chance when Schweinsteiger's pass found him unmarked in the penalty area, but the Hamburg winger failed to get a clear strike on the ball.
Podolski stabbed the ball goal-bound, but burly West Ham defender James Collins marshalled the ball over the line and the ball was cleared from the corner.
Referee Laurent Duhamel missed a clear mistake in the Welsh defence when Collins backpassed to Hennessey, who picked up the ball, but the Frenchman waved on play rather than award a free-kick.
It failed to matter however as Trochowski slipped his marker Edwards and pulled the ball back onto his powerful right-foot before he curled his shot around Hennessey on 72 minutes.
Germany had more chances in the game's final phase but Hennessey fended off a number of chances by Podolski and Helmes.