There is another thread (probably in deer resistance) that says that 6 feet is enough if it can't be seen through, otherwise 8 feet is safer

Thanks, dg. After a more thorough search of GardenWeb, it looks like the answer also varies regionally. Has anyone in the Hudson Valley actually had deer jump a 6' see-through (wire or plastic mesh) fence?

I had a deer wander into my garden (because I was stupid and left the gate open) and then frantically jump to get out of my six foot fence, and it took her a couple of leaps and crashes before she managed - so, I think they can do it - but it's quite hard. I've never had one get in (unless they use the gate!).

My fence is 7.5 feet and so far, so good. However, there is no doubt they can jump it if they are frightened or if a doe is being pursued by a buck. Maybe you could string a wire or barbed wire a foot above the top of the fence?

I saw on tv, on a gardening show, that someone hooked a car battery to the fence. Easily rechargable, and the deer get the message pretty quick.
I'm glad I don't have a drastic problem. I find a four four enclosed group of plants survive bambi-itis pretty well...

My fence is 5 feet tall and no deer have jumped it in 8 years. Knock wood. The fenced in area is 25' x 35'.

I make sure there are tall things like bean towers and staked tomatoes. This makes the deer cautious about jumping into someplace that will spear them (bad vision).

the good ole deer is CT can clear those fences in a heart beat ,,,,, espcially if they are in the inside and need to make a quick get a way .... my property borders on the reservoir and they have an 8' foot with additional 2' of barbed wire on it ,,that does the trick and protects one side of my yard ,,of course they come from the other direction !!

I've been using 4 foot chicken wire, deer have been kept away along with the woodchucks.

They can definitely clear 6 feet no problem. I think the question is: how big is the area you're trying to enclose? They don't like to jump into a small area. They don't like to jump into an area where they can't see what's on the other side. If it's a relatively small area they probably won't bother to jump in--unless they're really hungry, like in the winter. If you had some evergreen azaleas growing in there I bet they'd jump in over the winter. But it all depends on how hungry they are and how much effort they're willing to expend to get at whatever's inside. Ask around and see what works for neighbors with similar size plots.

I had the same exact question. This is the best advice I could find:

"...the best deer control answer here is not to raise the fence but to angle it outwards...a short metal extension at 45 degrees and carrying several monofilament cables will provide far better deer control in open spots than raising the deer fence two or even three vertical feet"

Here is a link that might be useful: Deer Fence

Greenhouseman had a great answer. 6 ft. is very jumpable unless you have an angled top outwards, or inwards if you make sure that part is visible. Another thing to think about is having something about 3 feet inside the fence that acts as a landing deterrent. Boulders or hedges/large plants can act as a landing obstacle and deer do not want to break their legs or ankles. A 4 to 5 ft. fence with a hedge running along it placed at the landing distance from the fence would do the trick.