Deer can be a major pest in the garden and can cause massive amounts of damage to your plants. The best way to keep deer off of your property is to install a fence. Some deer can jump to a surprising height and the fence needs to be at least 8 ft high. If your fence is too small, the deer will likely try to jump it, something you wish to avoid as a deer can easily become injured in the process. Alternatively, you can construct a slightly lower fence which has a 45° slant at the top. Deer are unable to jump high over a great distance so this is also an effective barrier. A third design option if you already have a lower fence in place is to build an additional fence 4-5 ft away from the first. Deer are unlikely to risk jumping both. In all cases it is imperative to ensure that there are no gaps or weak spots in the fencing as a deer will quickly learn to exploit them!
If you only have a small area you wish to protect then you could try caging your plants with wire mesh or deer netting which you should be able to find at your local gardening store.
Wooden deer fence