Deer in the garden
Deer can be both stubborn and agile backyard feeders, jumping fences and hurdling barriers to feed upon yard-grown greens. The most consistent way to ensure that deer remain on the outside of the yard is the construction of a yard-surrounding eight-foot fence. Fortunately, there are less time and cost intensive deterrents which can be used. Unfortunately, they are not nearly as effective as the 2.4 meter fence.
European bittersweet, Solanum spp.
Ferns
A medium sized or larger dog in the backyard is usually all that is required to keep the deer away.
The success of either type of these repellents is measured by damage reduction as opposed to damage elimination. Factors limiting the effectiveness of the commercial repellents include the size of the deer population, rainfall, weather, availability of other food and the deer's level of hunger. Different commercial produced repellents are based on rotten eggs, decomposing meat scraps (will attract scavengers or predators such as rats, raccoons coyotes, bears, mountain lions), capsaicin and chemical compounds.
There are also several deterrents which use the deer's fear of the smell of humans. Needless to say if you live in an area in which the deer have consistent contact and interaction (hand feeding) with people, the success of these techniques will be at best, limited. Onion bags filled with 2 handfuls of human hair or bars of soap suspended on branches or fence posts have been used with some reported success in rural areas.