If your not concerned with appearance you can make a very strong tall fence by weaving the branches vertically through rails. They come out the top in a vee. You can let them be as tall as you want. Trimming the tops all the same lenght will keep it from looking to crazy. Branches used in this manner can be 1.25″ in diameter. To keep deer out the spacing could be about 6″ to 8″ apart. The first wattle fence I built I used this method. It was strong enough to keep horses in.