To keep squirrels from digging in your flower pots take some wire mesh and wrap it around the plant inside the pot.
The wire mesh will prevent the squirrel from getting into the flower pot and digging around.
You can buy the wire mesh in rolls at Home Depot or other hardware stores pretty cheaply.
You can also keep the squirrels fed with some squirrel feeders and when they are not hungry then they will usually stay away from the flower pots.
Or setup a motion activated sprinkler system where the squirrels get sprayed with water when they get near your potted plants.
The squirrels will eventually learn to stay away from the potted plants.
Another option to keep squirrels out of your flower pots is to put some used coffee grounds around the base of the flower pot.
And also put a little coffee ground on the soil and in the soil and the squirrels will stay away because squirrels hate the smell and scent of the coffee grounds.
The coffee grounds will also help your flowers grow better as well.