Building a rustic fence out of tree branches can set your home apart as one that is creative and unusual, lending it an organic, back-to-nature feel. Branches can be great fencing material because they don't cost money, especially if you have a lot of trees on your property.
Find some nice hardwood branches, which will not rot as much as the soft woods (see Resources). Make a plan for how long you want the fence to be. Also consider how high it will be and how much light you want to come through. If you want more privacy, consider building a wattle fence from sapling branches.
Lay out your branches along the length of the desired line for the fence. Make sure that you have enough branches to cover the distance, and maybe even some extra in case a branch breaks or is not what you need for a certain section. It never hurts to have more than enough branches before you begin.
Dig the post holes for bigger branches that will hold up the fence. Place the branches that will act as fence posts into the holes, fill in the holes with soil and tamp the ground to pack the soil around the branches. Determine the distance between post holes by the weight and height of the fence. Taller, heavier fences should have posts closer together. Smaller fences do not need as much support.
Tie or nail cross-braces to the posts. If you want to use rope, tying a square lash works best for branches that are perpendicular to each other. You could also use wire. Determine how you want the fence to look before you decide how to secure the smaller branches. If you really enjoy the backwoods pioneer look, then the lashing may be the way to go, although it also requires the most time to do.
If you prefer more privacy, consider building a wattled fence. Wattle fencing is constructed from fresh saplings that are still flexible. The saplings are woven in and out of posts that are placed close together, so that the finished product resembles a giant wicker-type weave.
Glue or wire smaller branches to the fence cross-braces. Nails might destroy small branches.
Get someone to help you, especially if you decide to use lashing in your project.