Like most people, Germans love to receive flowers. But be careful: if they are wrapped in paper (not cellophane), as they usually are in Germany, make sure you unwrap them while you're waiting on your host or hostess's doorstep. You should be ready with flowers in one hand and a ball of paper in the other. You should offer the flowers unwrapped to your host or hostess.
Don't worry, it is their job to take the paper off you discreetly when you enter.