Q. Does anybody know of a way to keep cats from using my garden and potted plants as a toilet?
I found a remedy which works for us. I hope it does the same for you. We sprayed the plants with a solution of a little cayenne and water. It's nontoxic to the animals, doesn't hurt the plants, and boy, the cats sure hate the smell of it when they sniff around to prepare to answer nature's call.
One is to put human hair around your plants (on top of the soil). It's my understanding that animals hate the smell and are deterred from it. Any hair salon would probably be more than happy to sweep some up into a bag for you. Another is one my neighbor uses. She puts moth balls around her plants. Again, I think it's the smell. I don't know, however, how viable either of these options are for a food garden.
Moth Balls--place a few around the edges of garden, flower area, in pots, etc.--keeps them TOTALLY away!!! And doesn't hurt the plants or vegetables at all.
This is cat repellant recipe I heard on a radio gardening show that featured a well respected garden expert. Her formula is simple:
2 parts cayenne pepper
3 parts dry mustard
5 parts flour
Mix it together and sprinkle where ever you wish to repel cats. It must be reapplied periodically and after a rain.
I took plastic canvas of a complementary color, matching the flower pot, or using brown to blend with soil, and cut a cover to fit round the plant. My cats can not dig in the dirt, so they go elsewhere to "do their business".
If you place some lemon peel or any other citrus peel on the soil of potted plant, the cats should leave the flower alone as they do not like citrus smell.
I use aluminum foil or pine cones around the bigger plants, put cayenne pepper on the soil of the smaller plants. However you questioned "pot plants" and I don't have a tip, except to plant some catnip for the kitties.
My cats used to dig in the houseplants, which would annoy me to no end. So, one day I decided to cover the surface of the dirt in the pots with large pine cones that I had picked on a hiking trip. It worked! No longer did the kitties mess with my plants. The pine cones added a decorative flair, too. However, I now have three children, one of whom loved to grab the pine cones. I solved this problem by tying a large pretty scarf around the plant and covering the pine cones. No more hassles!