Here in Colorado, deer on the highways have always been a concern and
are becoming increasingly moreso (due in part to our high growth rate
and people crowding them out of their natural habitat). The highway
department has fenced many miles of road with 6-foot high dog-wire
style fencing, which deters most of them, that is, if someone doesn't
leave a gate open somewhere! Also, there are these nifty one-way exit
gates that allow animals to get out of the highway right-of-way, should
they accidentally enter it. I would think that a 6' ft. fence around a
garden would offer adequate protection, aesthetics aside.