The only sure way to get rid of groundhogs is to use a kill trap that crushes the animals head. Consider using a live trap, and bring the groundhog several miles away, with advice from the owner of a pest control business in this free video on home pest control and management.
Hi, I'm Jim Harman, California pest management. If you grew up on a farm, you probably are familiar with woodchucks, groundhogs, but as we push more and more of our homes into the farmlands and we start making it into our urban settings, or suburbia, we run into more and more of these wildlife pests that were in the farms. Now they're taking over and going into our backyards, into our backyard gardens, our landscapes, and creating a major pest. Groundhogs are rodent pests that will feed on almost anything. They destroy plants. They've been a problem for farmers for years. Unfortunately there's not much you can do. One product, called Ropel, which is a mothball type of product in a long rope, you can place that around thee outside. It's gotta be redone every two to four months, around thee outside of the house. That prevents them from coming up to the house, and puttin' around your property, well, hopefully you got a small size property 'cause the stuffs not that cheap, and it still has to be redone, and you're going to have that smell of mothballs constantly. Now if you've got one on your property, trapping is the only way really get rid of 'em. There's a kill trap called a Shear Grip Two-Twenty. That is one product that does work. It is a kill. It basically crushes the head as they're coming up out of the burrow. There's another couple live traps. You pick 'em up and you have to take 'em literally, other side of town. Get 'em at least five to ten miles away from your property. Other than that, that's the thing you really can do. Good luck.