Have you considered a tether so your dog cannot reach your flowers?You could walk your dog, great exercise for both of you.
Joan...My suggestion is to have you son with the dog on a leash and take it to the proper place to do his business. Hopefully he will then learn where to go. Good luck
Training and motion sensor sprinkler
Unless the dog is trainer not to pee there he will continue to do so.
Time to start training! I taught all my dogs where they welcome to do their business. Not that hard, but it does take time and patience. Lots of on line tutorials. Here are a few sites to get you started.
Dogs tend to avoid citrus scents, or oil of rue. Try spraying the area with the scents, mixed with a few drops of lemon scented dish detergent in water, which increases "sticking power". Dogs will also tend to avoid areas interplanted with strongly aromatic plants such as marigolds, lemon balm, rosemary, rue, basil, etc.
Dig up the plants?
You need to train the dog!
I love my dog so much but it constantly did the things that irked me most. It would chew on things that it shouldn’t or jump up and down out of the blue. Whenever I put on the leash, it would pull on it. Whenever it was out of the house, it would continue digging on the ground - I wish I could tell what it was looking for down there. All the things it did left me feeling depressed as if I failed it monumentally.
But since I discovered Brain Training for Dogs and applied the system offered, it now behaves the way a beautiful dog I always expect of.