Most people react to deer, groundhogs, and rabbits with a smile acknowledging their adorableness. But gardeners know better. Mammals might be cuter than insect, but their appetite can far more negatively impact your garden. Prevention is all about measuring the degree of damage and acting accordingly.
First steps: Turn first to natural deer deterents if the garden damage and the deer numbers are low. Failing that, rotate the use of human hair (try collecting from your local barber shop), soap (cut one bar into sections), and mothballs. Hang any of the three in open mesh bags near crops about three feet off the ground.
Final steps: If the number of deer snacking in your garden is just too high, an electric fence is the most effective choice. It can be done with fairly minimal cost, using a single wire attached to fiberglass posts with a high voltage charger. Even just temporarily electrifying a fence will make a big difference.
First steps: Clean your garden of any debris (excess brush, large stones, and so on) that might encourage rabbits to hide. If they don’t feel safe, the rabbits won’t take the chance. Trapping and releasing a few miles away from your garden can also be an effective deterrent. Bait the traps with fruit; I recommend apples.
Final steps: An effective fence needs to be buried at least 10 inches into the ground and sloped outward. Otherwise the rabbit can, and will, dig underneath. Creating fencing for individual plants and trees will keep anything particularly precious in your garden safe.
First steps: Treating your garden with coyote urine, Tabasco sauce, or scattering about human hair can interfere with groundhog munching if you have a limited infestation.
Final steps: Laying chicken wire on the ground, then affixing another sheet perpendicular to the first that’s held up with wooden posts will create a fence that prevents the groundhog from digging underneath.