When planting native, many are discouraged to find that deer are often a little too grateful for our efforts. I think it's important to plant things they will eat, too, as they are part of a balanced ecosystem, and may someday be valuable to us as a protein source. Here is how I protect new plants from deer browse:
4 foot round steel fence post ($2.50 at Menards & TSC) are easier to install than fence posts, cost less, and you don't need a fastener for the caging
Chicken wire, cut into 3-4 foot lengths (fencing can be used, but costs more)
Cut fencing or chicken wire so the cage is slightly larger around than the new plant you're caging.
Pound or step the stake/post in until the entire anchor plate is buried. This helps prevent or slow heaving out during freeze-thaw cycles.
Weave the fencing onto the post. If using chicken wire, it typically has a memory and will hold itself closed without any assistance.
If the plant is taller than the cage, or nearly as tall as the cage, shimmy the cage higher up on the stake to cover the area that deer are most likely to browse as they pass by. This can also be done as your plant grows taller. If your cage is too low, deer WILL nose into the top of your cage to nibble. They generally will NOT stoop down to eat below it.
Check your cages periodically. As the ground freezes and thaws, the stakes will loosen over time. When the ground is soft, stakes can be easily pushed back in by applying pressure to the anchor plate with a well-placed boot heel.