Bathroom Behaviors

Hey all, I need some help from all of you cat lovers.

Our neighbors have an outdoor cat which has taken a liking to using our flower garden and yard as her own personal toilet. There is cat poop everywhere.

Does anyone have any suggestions on a soil application or other technique that would persuade the cat to not defecate in our yard that would not be harmful to either the cat or the flowers?

Here is a quote from "peeing problems" in the sticky above.
"Take a Tea bag, then once used and its cooled, pour a few drops of OLBAS OIL on it. Olbas oil is a herbal remedy ideal for colds and completely natural. Health food shops as well as pharmacies sell it here and its cheap enough.
Then place the Tea bag with this smelling stuff on a small food bag and place it in the vicinity of where the cat has been urinating.
They hate the smell and he's given it a wide berth ever since"
I also learned that spreading some "human hair" in the vicinity keeps them off too.
And well, I have outdoor cats and they're the ones keeping feline visitors out too.