I have deer fences up to about 7 feet just to be safe. But I'm also growing hedgerows to one day replace the deer fences. The hedgerows are planted so the outside plants are good for deer to eat but are plants that get denser with more browsing. The plan is that the deer will just move along the hedgerow browsing the outside plants and not try to get in. Plus, I'm growing the hegerows to be 15-25 feet tall and very dense and 7-10 feet thick :)