I understand that broccoli is their favorite vegetable. If u could apply some poison to it and place in or around their den, they might chow down on it. I'm really not an expert in that area. There are kill traps that that they sell too.Is the goal to kill or just to repel? Do u care if they suffer? I can place a bullet between their eyeballs and accomplish the same thing without any suffering and at minimal cost. The groundhog is a rodent by the way...
Placing a fence around your garden might ward them off, but they might dig under it. Placing some stinky smelly stuff on some
plants to repel them seems useless (and perhaps costly).U must trap them alive or trap them dead, or kill them some other way.
It's funny... the bigger the animal, the more guilt people have about killing them. If it was a mouse or a Japanese beetle, u wouldn't give a d*m.
U torture those japanese beetles by letting them swim in soap water... LOL Don't feel guilty about torturing groundhogs...
I'm not advocating torture at all... just trying to help solve your problem. If u depend on my garden for my family's livelihood or sustenance u don't need to be playing around. U r in New York and your
growing seasoning is about over at the end of August.