- http://www.flickr.com/photos/what_i_see/140238947/
If you look at a garden from a dog's point of view, it's a great playground. It has wonderful-smelling fertilizer and plantings, it might have moles or mice or rabbits hanging around, and sometimes it even has food.
One deterrent is to set up a spray sprinkler that you can switch on if your dog goes near the garden. You'll need to be watching your dog when it's in the yard so you can turn on the spray, until he learns not to go near the garden. A good thing about this method is he won't associate the sprinkler with you -- he'll just learn that going to the garden causes him to get sprayed with water.
The sprayer must be high-powered enough to make the dog want to stay away from the garden. A nice light water sprinkling isn't going to bother most dogs, particularly on a hot day.
A water pistol will also work, except you have to actually be in the yard to use it, and the dog will realize that you were responsible. - http://www.flickr.com/photos/re-ality/239136164/
You can provide your dog with an acceptable place to dig, an area of bare earth where you can bury some toys and bones, so the dog knows he can find treasures here and have fun. If the dog starts digging somewhere else, stop him with a loud noise and state the command "No dig." Bring him back to the assigned area and praise him when he digs there. This might sound more difficult than it is, but you've already accomplished something similar when potty-training the dog to go outside rather than inside. - If your dog keeps digging in the same places, try putting some of his feces in the holes. Few dogs will dig through their own waste matter.
- Dogs often dig a hole under a shade tree or next to the house, to lie in and stay cool. If you've made sure your dog has shelter from the elements, and your dog still prefers to lie in a hole, again, providing an acceptable place to dig is a good strategy. A big hole under a shade tree is probably not too inconvenient, and may not even be very noticeable if it's by an evergreen tree with branches near the ground.
- Different types of fencing can be good deterrents. Burying the bottom of the fence at least a foot below the ground, placing chicken wire at the base, adding concrete to the base, or anchoring chain link fencing to the base with some laid on the ground around the fence, are all possibilities.
If your dog is so determined to dig that none of these ideas works, you can stop your dog from digging in certain areas with an invisible electric fence. The kit includes a dog collar which delivers a mild shock if the dog comes too close to the fence. It's best to spend a little extra money for a collar that gives a warning beep before delivering a shock, so the dog learns to avoid a shock altogether.
You will need to mark the fenced areas with flags or some other object the dog can take notice of, then train him to stay away from these places. This involves walking him there several times a day and saying "no" when he gets too close and the collar beeps, and then gently tug him away. Once the dog is routinely avoiding the flags, you can start removing them. Expect to spend a week or two training your dog to avoid an invisible fence. - If your dog stays in a fenced area all day while you're at work, he's probably going to dig no matter what you do, because he's bored and lonely. Make sure to spend time exercising the dog when you're home. Take him on a couple walks, and play fetch or other fun games. Provide busy-box toys, chew toys, and Kong-type toys to keep him occupied when you're not there.
If he continues to dig no matter what, you really will need to accept his needs and fill in the holes.
