18" above ground would do the trick but when they do these measurements it includes the bit that stakes into the ground. Won't deter most dogs/dog owners are too checked out to notice

Last summer I renovated my garden and despite creating a gravel barrier between the sidewalk and my beds, I can’t keep neighbors from letting their dogs dig, explore, and mark my gardens. I don’t think a sign would be effective and my husband won’t go for a tall fence. Do you think an 18 inch garden fence would send a strong enough message? My neighbors aren’t malicious, just clueless.

Thinking something like this: https://plowhearth.com/products/5692