To get more detailed information on the german WWOOF hosts including addresses you need to become a member of WWOOF Germany.
You can do so by registering as a member.
You will be sent an email confirmation after successful registration. It includes your password and a confirmation link.
After confirming your registration you will need to transfer the membership fee.
Use PayPal or money transfer (Euros only!) to do so. Your membership is valid for one year.

Once the payment is confirmed you will be able to look at the German WWOOF hosts' contact details online at via login.

There are two different types of membership:
Only online access, fee 20.-€/year:
entitles you to access the host details online. (it's not possible to print a host list!)

Online+printed host list, 27.-€/year:
entitles you to access the host details online plus a printed host list. (printed host list = German version translated to English)