Traditional woven-wire fencing must be a minimum of 8 feet tall to successfully exclude deer, says H. Peter Loewer, author of "Solving Deer Problems." Angling the fence's top 12 to 18 inches outward or increasing the height with two or three additional strands of high tensile wire will reduce the deer's chances further.
In low-traffic deer areas, a quick-to-install, inexpensive electric fence that uses one wire suspended 30 inches above the ground often proves to be an adequate deer fence. High-traffic deer areas may require multiple, evenly spaced wires but the fence typically doesn't need to be more than 30 to 36 inches tall.
Ideally, you should install your deer fence before planting seeds, trees or crops. This keeps the deer from developing the habit of coming to the off-limits area in the first place. Check your deer fence at least once weekly and do repairs promptly to minimize repeat visits.