Answer: How sad for you! I hope your remaining plants recover! Epsom salts can be sprinkled on the vegetation and fruits of your garden plants to render them foul-tasting to groundhogs. The good news about this strategy is that Epsom salts will also help some of your garden plants to grow better. But the bad news is that rain will wash off the Epsom salts, meaning that you will need to make repeated applications.
Another strategy that suffers from the same drawback is discouraging groundhogs with foul-smelling agents such as ammonia. Ammonia-soaked rags can be strewn along the perimeter of your garden, forming a stinky barrier to repel groundhogs. But even ammonia's smell fades eventually and a re-application will be necessary.
Fences such as hardware cloth or chicken-wire fences can provide a more permanent solution to your groundhog pest problem. Be aware of two factors, however: groundhogs can climb over your fences, and groundhogs can tunnel under your fences. To discourage the former, make your fences 3'-4' high. To foil tunneling attempts, the University of Missouri Extension advises:
"The buried portion of the fence should be bent at a 90-degree angle, 1 foot below the surface, with the bottom of the fence pointing away from the garden. This design discourages burrowing if it is started at the fence line."
For many gardeners, live-trapping groundhogs as they exit their burrows is the preferred method of pest control. However, this means you'll need to find a safe place for relocation of the pesky critters.
Best wishes with your garden!
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