Think of her as a conflict-resolution specialist — except that at least one party in most every dispute that Marne A. Titchenell of The Ohio State University negotiates is a four-legged, fur-bearing individual stubbornly disinclined to negotiate.
“In the past week alone,” said Ms. Titchenell, whose official title is wildlife program specialist, “I have answered skunk, groundhog, bat, vole and mole questions. And, of course, ones about deer.”
Ms. Titchenell’s primary professional role is educating Ohioans about wildlife ecology, biology and habitat management. When she lectures to gardeners, farmers or the nursery industry, she asks for a show of hands (virtually these days) from the audience when she names challenges they have faced. Then she runs through photos of animals that in backyard or agricultural settings may be referred to as “nuisance wildlife.”
“By the time I get to deer,” she said, “most people raise their hand.”
And then, although they have probably signed up for the talk hoping that she will deliver the elusive grail of a “deer-proof” plant list, Ms. Titchenell has to deliver the bad news: “No plant is safe from deer under all conditions.”
A big, serious fence starts to sound pretty good when you consider the white-tailed deer’s formidable credentials. As the dominant species in Canada and the United States, east of the Rockies, it is the largest herbivore in most places where we farm and garden (unless you have moose, elk or bison … or your neighbor’s horses or cows are on the loose). And in our shared environments, deer have few predators, other than us: as hunters, and as automobile drivers.
They have been documented as consuming hundreds of plant species, Ms. Titchenell said, and they adapt their diet seasonally. As green foliage wanes in the fall, they move on to the fruits of shrubs and trees, including acorns and beechnuts, and then to twigs, buds and bark.
Even plants that are not on their preferred list may get a casual taste-test — which can be costly, if it’s a woody plant that is disfigured.
And there’s more: From August and throughout the fall breeding season, bucks in rut can rub the bark off trees as they remove velvet from their antlers or leave scent marks behind. Tree tubes (for seeding or saplings) and individual wire cages can help there.
Are you frustrated by trying to design a garden that deer won’t touch? Ms. Titchenell suggests a “toolbox approach” of strategies: excluding animals with a barrier; repelling them with products that smell or taste bad, or both; scaring them; or modifying the habitat.
The greatest success comes from knowing each tool’s limits and employing those best suited to your particular conditions. But even then, the key is staying alert and ready to reassess the situation as the deer habituate to your efforts.
First, though, make sure your adversary is a deer.
Who Ate the Hosta?
Just because you saw a deer doesn’t mean that’s who mangled the hosta or the row of bush beans. You may have rabbits or woodchucks, or all of the above.
With larger plants like shrubs, look carefully at the height of the damage. Rabbits and woodchucks generally browse lower, up to about the two-foot level. Deer, which can reach a browsing height of six to eight feet, often feed on shrubs from the top down or from the sides.
On all plants, and especially the smaller, herbaceous ones, the most distinctive clue may be in the edges left behind. Are they torn and jagged, rather than clean-cut? Deer have distinctive dentition, with bottom incisors but none on top.
“They grasp a plant between those lower teeth and that upper palate, and pull — and it tears, whether it’s leaves or a branch,” Ms. Titchenell said.
Rabbits’ sharp incisors make clean cuts, often at remarkably close to a 45-degree angle; woodchucks are also pretty tidy.
So you’ve determined that your problem is deer — but how many, and how entrenched are they? A control plan starts with a realistic assessment of the current deer pressure, and how much pressure you can personally tolerate.
Ms. Titchenell’s general guidance: Mild pressure means that plants suffer rare or occasional damage. A garden with moderate pressure experiences consistent damage to certain plants (maybe deer favorites like that hosta, or tulips) and some loss. In high-pressure areas, many plants are consistently damaged, with substantial loss.
What Repellents Offer (and What They Don’t)
Repellents to deter deer and various other wildlife are on every garden center’s shelves. But they can be costly and require repeat applications. Also, they are not appropriate on edibles, and only work well in relatively small areas of low to moderate deer pressure.
As Ms. Titchenell put it, “If they’re used to eating your plants, highly motivated animals will ignore repellents.”
Repellents work by smelling bad, tasting bad, or both. Those that work by odor alone may contain blood, garlic oil or eggs. Bad-tasting ones list ingredients like capsaicin (from hot pepper), blood or eggs. Notice that eggs (sometimes referred to as putrescent egg solids) are on both lists — and often recommended in research.
Carefully read the product labels, Ms. Titchenell advised, for ingredients, safety guidance and frequency of application, because the dollars and the time can quickly add up.
Claims of “rain resistance” go only so far. And even in a dry spell, new growth that appears after you last sprayed requires a repeat application. Alternating products as animals adapt to one brand may help — but again, don’t expect complete control if you have motivated animals.
If You’re Ready for a Fence …
So you’ve tried repellents. And maybe even scare devices. (Hint: The element of surprise and variability is key, said Ms. Titchenell, who prefers motion-controlled sprinklers to other scare tactics because their placement and jet height can be changed up.)
After employing everything short of fencing, only to suffer recurring losses, many gardeners wish they had built a barrier from the start.
“If the deer really want to get to your food source,” Ms. Titchenell said, “aside from a very tall exclusionary fence, all bets at protecting it are off.”
Fences can be of varying heights and materials, electrified (where local code allows) or not, and permanent or seasonal — to protect a vegetable garden, for instance. Some electric fences are less obtrusive and cheaper, as they don’t require heavy-duty fence posts. But they are not as effective as physical barriers like an eight-foot or higher woven-wire fence, or even heavy-duty polypropylene mesh reinforced with wire and flagged at intervals with streamers to alert the deer not to bound into it.
What if you don’t like a completely caged-in look but you want the height? A hybrid could be fashioned from a picket fence with eight-foot posts supporting each panel. Above the pickets, stretch heavy polypropylene (like that sold at Benner’s Gardens), reinforced with wire and flagged.
Around smaller garden areas, a solid stockade or mesh fence of perhaps five feet may suffice. Deer hesitate to jump into areas they cannot see into, or into confined areas where they fear they may be trapped.
Electric fences do not exclude animals, although they can modify behavior with negative reinforcement. But with any electric fence, the wires must be kept clear of vegetation or the current will be interrupted.
One electric fence that Ms. Titchenell recommends for low to moderate deer pressure is the peanut-butter fence, a simple design of one or two strands of 17-gauge wire — one at about 30 inches, or wires at about 10 to 12 and 30 to 36 — with the added enticement of a lure, plus flagging. Strips of aluminum foil dabbed with tempting peanut butter are crimped and strung or taped on the upper line. Some gardeners bait prefabricated rolls of electrified rope or net fencing this way (from sources like Premier 1). In either case, the deer get the message when contact is made with a nose or tongue.
But What About Deer-Proof Plants?
And then there is that magic plant list we seek, the one that starts with how fuzzy leaves (think lamb’s ear) or spiny plants may be less palatable to wildlife. It all sounds very logical, until a deer eat the tops off your thorny rose canes.
Also frequently mentioned as safe are plants containing latex saps, like milkweed (Asclepias) and annual poppies, and other “toxic” compounds (Narcissus and foxglove are often cited). At the other extreme, those lists warn us not to even bother with arborvitae (Thuja), rhododendrons or yews (Taxus).
Maybe the most deer-resistant garden is one of herbs, as aromatic plants like artemisia and lavender get high resistance marks.
The term “deer-proof” is not used even for herbs, however, in one of the most extensive online resources, Landscape Plants Rated by Deer Resistance, from Rutgers University’s New Jersey Agricultural Experiment Station. The most resistant category there is “rarely damaged.” Next comes “seldom severely damaged,” then “occasionally severely damaged” and “frequently severely damaged.”
But regional preferences differ, so even a tool that comprehensive cannot be all things to all gardeners. (Here are some sample lists from other regions.)
“Deer are a challenging species to manage,” Ms. Titchenell said, “one that requires patience and persistence on the gardener’s part. Understanding how to best use the available tools, remaining vigilant and working to bring damage down to a tolerable level are the best strategies one can take.”