It took 15 minutes for the first shots of the match as first Monchengladbach's Juan Arango and then Hannover's Didier Ya Konan failed to find the target.
The hosts began to take hold of the game and Thorben Marx saw a low shot saved in the 27th minute before a goal came.
Sergio Pinto almost equalised for the visitors before the break, but his shot from outside the area curled just wide of the upright.
After the break, Herrmann came closest to scoring the second of the game when he found space in the area but dragged his shot wide.
Ya Konan then missed a pair of opportunities to bring Hannover level. The Ivorian couldn't test Marc-Andre ter Stegen with either his close-range shot or header.
The match ended on an even more sour note for Hannover when Pinto was dismissed for a second yellow card with five minutes on the clock.