There is no general minimum wage here, but there are minimum wages possible for individual branches, also there are laws that make too low wages criminal (Less than 2/3rd of the average wage for the job)
http://www.nrwinvest.com/Business_G...social_security/Terms_of_Employment/index.php
The whole mess is a bit more complex here, the tariff autonomy in Germany is part of the constitution, so the government does only have the right to intervene in extreme situations, at the same time, the unions and employee organizations have more legal power here, than in many other countries.
If you do all well as company owner, your employees will not negotiate against you, but rather really focus on getting a fair share of the profits (Volkswagen is, despite the huge corruption scandal in their union, still a good example).
But there are also many black sheep around, that show that the laws aren't really sufficient. There was for example a company, that made membership in a fake union mandatory, often without telling the new employees that they just joined a union when they signed the paperwork for the new job at their employer. This just gets slowly rolled up, and by the evidence that is slowly gathered by journalists about the scale of the criminal energy there, the fake union and all involved companies will face a very hard time: Even if the justice might just give these bosses a small slap on their hand, the real unions will be not so friendly and usually don't forget such mistreatment.