Suggestions for keeping groundhogs out of my garden?

My neighbor has a groundhog living under their porch. They don’t seem to mind and neither did I, until I found one of my tomato plants had been eaten. I’m 99% sure it was him because I’ve seen him hanging out in my driveway.

Most of my garden is fenced in, so that should help, but I have a couple tomato plants in large planters that I’m now worried about.

I sprinkled some peppermint oil around the planters because I read that might help. I have a cat, and read used kitty litter may scare it away… but that seems a little gross tbh.

Anyone have any hog-repelling secrets?