Not sure if this will help but when squirrels started digging in my opened wintersowing containers I bought some mosquito netting & covered them with it. No problems since. This is good for tiny seedlings and small plants. Once they get larger (fill most of the pot) I take it off and the squirrels leave them alone.
Critter Ridder also works well, especially with skunks and stray cats. But if you use the spray make sure it isn't windy. It's pretty potent and not something you want to get a face full of!
