There is no perfect method to preventing deer from coming on a property or chewing up plants in a garden. Many people think a fence will do just this but unless you are willing for the yard or garden to look like the county jail, this simply is not going to happen. Deer have been known to jump fences as high as eight feet in order to get to fresh food.
This means that unless you have the ways and means to install say, a 10 to 12 foot fence with voltage running thru it and Constantine wire around the top, the garden or yard is still likely at risk. Most people simply cannot afford this nor do they want that type of look on their property. This brings it down to ground level protection.
Electrified fences work well, provided the deer actually touch the fence. A 4-foot high fence is a bump in the road to most deer and if the property is big enough, this is cost prohibitive. The next logical step would be to treat the plants and trees in the area with some type of spray on repellent.
The spray on ones work well enough but still allow the deer close to the plants. These will, however, keep the deer from eating them or destroying them by stepping on them. The majority use an odor based repellent and if this is strong enough, the deer rarely even come into the area.
Be wary of the homemade recipes for some deer repellents. While these do use all natural ingredients, many call for the use of eggs for the odor portion of the repellent and this can stink up a garden something fierce over time. There are quite a few good spray on ones on the market that are strictly offensive to deer and small animals and leave the senses of humans untouched.