I kind of feel stupid for asking this, but where is Esther's garden? I need to grow black hibiscus for her quest and I was told that it would be quicker if I grew it in Esther's garden (considering it takes a few days in the normal gardens). I even googled it, but I can't seem to find Esther's garden and I would very much appreciate a link :D or am I missing something here?

I don't know for sure since I've yet to get that type of quest but I have read that it's the garden in Ceteropolis. That's the only other garden I can think of.

http://subeta.net/explore/centropolis_cleanup.php

This was actually the garden I needed, thank you so much! :)

Glad to help! :)