Have you tried squirrel repellent? Spraying around the area they are digging up might be a solution.
Hi Judi: Those squirrels, they are a caution! Basically, you can't get rid of squirrels. Feed them somewhere else, and remember, everything needs to eat, so if you can, learn to enjoy the little buggers. I will say that they climb up my peach trees and throw peaches at me, but that's only when I forget to put something out for them:) If they are chewing on your plants, spray with a mixture of 3/4 water and 1/4 oil of clove (you can get it in the candy making section of the store, it's a bottle about 2 1/2 inches high and only costs a couple of bucks). Put this in a spray bottle and spray whatever you don't want chewed or clawed. Works for cats and dogs, too. Won't harm them, smells great, tastes terrible:( Another thing you can do is to put lava rocks around your plants. They hate digging in the sharp rocks. So do cats:) Good luck
Cinnamon or hot chili powder works if you sprinkle it around the plants. That might not be feasible though if you have a large garden. In that case, I would try PlantSydd. Good luck!