I have had firsthand experience trying various techniques to deer-proof a garden.  Our garden, on two feet of stone wall and completely surrounded by a 6-foot fence, manages to keep the deer out but the unprotected plants and flowers in the rest of the yard do not have similar luck.  Unfortunately, some of the most gorgeous flowers to me happened to be some of the tastiest options for deer.  For gardeners and others trying to keep deer away from plants, here are some techniques and resources to help. 

One method to prevent deer from eating your plants is to plant ones that deer do not prefer to eat.  Ann Flagler, a horticulturist in Sparta, N.J. mentions that mountain laurels, daffodils, andromeda, and plants of the mint family fall under this category.  On the contrary, Ms. Flagler says to avoid planting what deer like to eat, which include tulips, pansies, begonias, asters, and rhododendron.  Horticulture magazine adds phlox and hostas to the list of deer favorites.  Other lists of plants that deer dislike and more deer resources can be found on sites created by Cornell University and Barbra Bakker. 

Another way to prevent deer from devouring plants is to spray deer repellent, spread deer-resistant fertilizer, set an odor disliked by deer, or squirt deer with water.  One deer repellent is Deer Stopper, in a line of repellents by Messina Wildlife.  The Horticulture magazine recommends using spray or fertilizer such as Milorganite, dried blood meal, Plantskydd, Hinder, or Deer Solution.  The sprays Hinder and Deer Solution are approved for usage on plants or vegetables intended for human consumption.  Other repellents I've heard people say they use are Deer Out, Deer Scram, or bags of human hair.  Certain scents can be placed around the garden or plants to deter deer.  Ms. Flagler suggests that deer dislike cinnamon and garlic.  Horticulture magazine suggests keeping deer away by using Lifebuoy, Irish Spring, Zest, or any strong smelling soap.  Other unfavored scents are dried blood and coyote, fox, or bobcat urine.  Motion detector deer repellents, which are motion-activated sprinklers, especially ScareCrow by Contech, have been reported to work. 

One could also choose to fence in plants to keep deer away.  Deer have been known to jump 8 feet and higher.  For this reason, a fence 9 feet high should be more than enough to keep a deer out of an area.  I have heard of people angling their fencing outwards or also putting one fence up and then putting another fence around the first fence with about four feet of space between them.  This second option could be bad if a deer tries to jump the first fence and gets stuck in between the two fences.  Many people also tie white fabric to the fence, which is thought to make deer see the outline of the fence.   More information about fencing out deer or answers to fence-related questions can be found at the McGregor Fence Co. website.  A fence is often preferred because there is nothing left to do once it is constructed, whereas deer repellents and sprays need to be applied continuously.