I alternate between coffee grounds and citrus peels weekly. The scent rotation seems to prevent dogs from getting used to either smell.
Create a designated digging spot with soft soil away from gardens. Most dogs will choose the approved area if rewarded for using it!
Remember fresh grounds work better than dried ones. I refresh my perimeter every 3 days after rain or watering.
Oddly, coffee keeps my lab away but my beagle couldn’t care less. @iJennifer is right - it’s very dog-dependent.
For persistent diggers, a low decorative fence works better than any scent deterrent. Visual barriers + training = most reliable solution.
Coffee grounds may deter slugs too! Just be sure to use fully cooled, used grounds - fresh ones can alter soil pH too drastically.