Came here few days ago with my elderly mother. Bought ticket €8 for Herrenhaeuser Garten and the garden opposite (forgot the name).
Both are lovely and beautiful but we especially love love Herrenhaeuser Garten. Soo beautiful and wonderful!!! Love to see the fountain which will stop at 12 PM and operate again at 3 PM.
The garden was quite big and peaceful. Should spend few hours alone in this garden to enjoy the view and take picture.
The garden accessible by Ubahn (located just outside the garden).
Highly recommend place!!