How can I keep feral cats from using my flower beds as litter box?

https://www.alleycat.org/resources/how-to-live-with-cats-in-your-neighborhood/

For beds, it’s become popular to try dollar store plastic forks, tines sticking up throughout the garden, handles tucked into soil deep enough to hold them.

Let me know if you figure out a way to keep them off your cushions

Unfortunately you will not be able to unless you can totally barricade them out. I've had the same problem for years and tried many things with no luck. BUT recently I was thinking about going to a store where they sell hunting stuff, because you can buy bear urine. It might sound absolutely nuts, but we have fleas here because of the cats and we don't even have any animals! Both of my younger boys have developed ring worm (more than once) and the Dr says it most likely from the cats. They do their business in my veggie garden. I'm just sooo sick of them. But in my head, i believe if they believed there was a predator in my yard they wouldn't stick around

Try sprinkling chili powder in your flower beds. They do NOT like the smell.

I've read but not tried you can put predator pee around the perimeter of your yard. I've got a jar of fox pee (from Amazon) in my garage waiting for my courage.

Get a motion activated sprayer at your local diy store, it will spray them when they come near and kitties don't like to get wet.