Fencing Out Deer and Elk in the Bitterroot Valley

How tall does a fence have to be to keep deer out?

Six feet. Research at Montana State University has shown a six foot high fence is sufficient to keep deer out of a garden, and that figure is the practical starting point for any exclusion project in this valley. It is worth stating plainly because the number circulating informally is usually eight or ten feet, which makes people abandon the idea as impractical before they have priced the version that actually works.

The distinction that matters is between a deer's jumping ability and a deer's willingness. A deer can clear more than six feet under pressure; the point of the fence is that it will not routinely choose to, particularly where it cannot see a clear landing on the other side. That is why exclusion is about a well-built continuous barrier rather than about outbidding the animal on height.

Does the same fence work for elk?

Yes, and this is the finding worth knowing if you are anywhere in the Bitterroot. MSU Extension tested four different fence modifications across forty exclosures in southwest Montana, baited and monitored over two winters, to see what would deter both deer and elk. Six-foot woven wire was one hundred percent effective.

That is an unusually clean result for a wildlife-damage study, and it means a single specification handles both animals rather than requiring a heavier build for elk. The study was looking at high-value agricultural ground rather than residential yards, but the animals and the physics are the same, and a garden or an orchard block is exactly the kind of concentrated high-value area the approach was designed for.

Can you extend a fence you already have?

Often, and it is the cheaper route by a wide margin. MSU Extension's guidance is specifically to modify existing fences that are forty-eight inches high by extending them to six feet, and it gives two methods for gaining the height: welding rebar to steel fence posts, or drilling three-eighths inch holes in the top of wooden posts to take rebar.

The wider study makes the same point in economic terms — the whole premise of that research was that costs of erecting deer-proof fencing can be greatly reduced if an existing fence is modified instead of being replaced. If your property already has a stock fence, a garden fence, or a boundary line at a workable position, you may be looking at an extension rather than a rebuild. It is worth having someone assess what is there before assuming otherwise, which is part of what we look at on fence repair visits.

What about electric fencing?

It is effective under moderate to high deer pressure, and it is a genuinely different design philosophy: rather than a barrier too tall to clear, it uses wire spacing so that deer either attempt to go through and are effectively shocked, or are physically impeded. MSU Extension sets out an eight-wire design in detail — high-tensile wire on rigid corner assemblies, line posts set at thirty-three foot intervals, the lowest wire eight inches above ground, alternating wires connected to a well-grounded low-impedance charger providing at least two thousand volts, with the top wire grounded for lightning protection.

Two details in that specification are the ones people skip. The first is that you must clear and maintain a six to twelve foot open area outside the fence so deer can see it — an electric fence a deer does not know is there gets run through rather than respected. The second is maintenance: weekly inspection and voltage checks. An electric fence is a system that needs attention, not a structure you install and forget, and that is the honest trade against woven wire's higher initial cost.

What should you protect first if you cannot fence everything?

Concentrate the fence rather than extending it. Perimeter-fencing acreage is expensive and, on a large property, frequently unnecessary; enclosing the garden, the orchard block, or the newly planted beds delivers most of the benefit for a fraction of the fence line. This is the same logic the MSU study applied to ranch ground, where the recommendation was to fence only the key areas subject to high losses rather than everything.

Young trees are the other priority and need a different solution entirely. MSU Extension notes that a four foot high woven wire cylinder will usually keep deer from rubbing tree trunks with their antlers — that is trunk protection against autumn rub damage rather than exclusion, and it is cheap, quick, and prevents the kind of bark injury that can kill a young tree outright. Anything we plant as part of landscape design on a browsed property gets that conversation.

Do repellents and scare devices work?

Some do, with conditions, and MSU Extension is refreshingly blunt about which do not. Contact repellents make plants taste bad and area repellents work by odour; both are more effective on less-preferred plants than on something a deer really wants. Apply on a dry day above freezing, and treat to a height six feet above the maximum expected snow depth, because deer browse from the top down and a snowpack raises where they can reach.

On the other side of the ledger: ultrasonic devices have not proven effective in research trials. Home remedies such as bags of human hair or bars of soap hung in branches are described as questionable at best, with the note that deer have been reported to eat the soap. Motion-activated devices that spray water do work well. And a dog tied near the garden will often repel deer, which is the oldest advice on the list and still holds.

Can plant choice do some of the work?

Some, and it should be treated as reducing pressure rather than removing it. MSU Extension's framing is that initial selection of plantings may provide the best remedy to prevent deer damage to ornamentals, while being clear that no plant is deer-proof if a deer gets hungry enough. Preference is real and reliable enough to design around; immunity is not.

Two placement points come from the same guidance and are easy to act on: harvest garden crops as early as possible to shorten the window of vulnerability, and plant susceptible things as far as possible from wooded cover, since deer are far bolder within a short dash of somewhere to disappear into. Combining sensible plant choice with a fence around the one area you cannot afford to lose is usually the right balance on a Bitterroot property.

What does this mean for a fence you are building anyway?

If wildlife pressure is part of why you want a fence, decide that at the design stage rather than after. Height, mesh, gates and line position are cheap to specify at the outset and expensive to retrofit, and a fence built to six feet from the start costs meaningfully less than a fence built to four and raised later. Gates in particular are where exclusion fails, because a gate that is propped open through the working day is a gap in the fence.

A fence that has to do several jobs at once — mark a boundary, contain a dog, keep deer out, and look like something you want to look at — is a design problem worth spending a conversation on. That is how we approach custom fencing, and it is much easier to solve on paper than in the ground. Call HJ Property Care & Tree Service at (406) 493-8300 or request an estimate and we will walk the property with you.

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