How to stop the poo?

[jadams84]

We just moved into a new house and have found that the neighborhood cats love to use our children's sandbox as well as my wife's rose garden as their favorite place to poo. :(

Any ideas on how to discourage them? Thanks.

[SpencerTheLion]

Unpleasant smells like citrus or pepper odors repel cats. If you can cover the sandbox, that would be helpful, as some of the better litters are sand-like.