Before you start investing in deer deterrents, first assess whether those deterrents have any chance of working, suggests Leonard Perry, horticultural expert at University of Vermont. That means knowing something about their behaviors and food source preferences.
Deer feeding pressure is primarily a function of population pressure and alternative food sources. With too many deer, and too little food, they’ll eat almost anything. In this worst case, fencing may be your only effective control — besides legally-used ammo.
Perry recommends the book “Deerproofing Your Yard and Garden,” written by Rhonda Massingham Hart. It offers many tips about deer behavior and damage control. Some of them cross over for cropland. Wal-Mart offers it on the web for $8.80. You’ll find more helpful links at the end of this article.
With fewer than five deer per square mile and only occasional browsing and buds nipped in the spring, try repellents or more long-term landscaping choices, says Perry. If there are five to 10 deer per square mile, with damage through the summer including loitering and feeding during the daytime, you may try the same techniques first. If they don't work, you may need to resort to controlled dogs and fencing.
Finally, if there are more than 10 deer per square mile, with most plants being damaged and stripped to the ground, start with fencing and dogs. But work toward cooperative community controls, he urges. That’s where hunting comes in.
Short-term spookable only
Deer are afraid of anything new, so one tactic is to use several deterrents and rotate them frequently. That’s because deer learn quickly.
Deer also have a main goal — not getting eaten. Once they determine that something won’t attack or go after them, a deterrent may become ineffective in a few days. Keep deterrents mysterious or frightening to deer.
“With low population pressure in my own landscape,” says Perry, “I’ve successfully used motion-activated lighting [on a portable stand] for control. Yet when I fail to move it every few days, deer learn it is stationary and no threat.
“Then there’s the story of a neighbor with a chained dog. Once deer learned the dog was on a chain, and the length of the chain, they began feeding just outside the dog's range despite its frantic barking.”
Deer in wild country or rural areas will be more scared of humans than suburban deer. They get used to having humans around. That may be partly due to hunting each fall in rural areas.
Know their habits and tastes
As with humans, it’s easier to prevent habits before they become habits. The best controls often begin before there’s a problem. Start using deterrents in spring before deer visit your landscape or find your choice plants, and hopefully they'll pass them by. Consider this as educating your deer.
Remember, though, deer are adaptable. If they taste and like your plants, they may stick around despite your deterrents. As author Hart says, “Once they adapt to your garden, they adopt it.”
Once deer adopt your garden, you'll need a new strategy. Just like people, deer have different tastes, likes and dislikes. This helps explain why deterrents vary widely in effectiveness from one location to another, as well as “resistant plants.” You'll have to experiment and determine what works best for you. Remember, even on your worst day, you are smarter than deer.
Read two other articles on reducing farm-related deer damage:
Source: University of Vermont and Vermont Nursery and Landscape Association