2015/37 Employer may not treat involuntary garden leave as paid leave unless the employee can be certain he will be paid during the leave before it begins (GE)
If an employee is put on garden leave, his or her entitlement to annual leave can only be fulfilled by the employer by means, either of payment before the leave begins, or an unreserved promise of payment for all remaining leave.
Bundesarbeitsgericht (Federal Labour Court), 2015-02-10