Deer browse in winter and how to protect your plants

This guide is part of our Montana Winter Property Guide. Most of what follows comes from the June 2023 MSU Extension MontGuide, Minimizing Deer Damage in Residential Settings, written by MSU's wildlife and horticulture specialists with the Montana Department of Agriculture's vertebrate pest specialist. Our year-round guide to deer and elk damage to Montana trees covers antler rubbing and elk, so this page stays on winter browse.

How do you know deer did it?

Look at the cut. MSU explains that deer lack upper incisors, so they cannot clip plants. They twist and tear instead, which leaves a jagged or torn surface. Rabbits and rodents typically leave a clean, 45-degree angle cut, so the two are easy to tell apart once you know.

Height is the other clue. MSU says deer browse can occur up to six feet high. Damage low on the trunk and hidden by snow points you to voles instead: MSU's guide says that bark damage is usually on the lower eight to ten inches of the trunk, and our guide to vole trails and winter damage covers that. Bark scraping and shredded bark is antler rubbing, which MSU says happens in fall and early winter, mostly on immature smooth-barked trees such as aspen.

Why do deer eat more of my landscape in winter?

Mostly because their choices narrow. MSU describes deer as preferential feeders: ornamental plants are usually not their first choice, but that changes with the availability of forage, deer density, competition and how close your yard is to deer habitat. Many Montana gardeners see deer eat flowers and foliage in the growing season, then feed on tender buds and young plants in the fall and winter.

MSU also says deer feed on trees throughout the year, though less in summer because of abundant food sources. Its guide adds that dense cover is used for winter shelter, so a property next to timber or a brushy creek bottom will often see more pressure.

Which plants are most at risk in winter?

Young ones. MSU says younger, more tender and newly transplanted plants are often damaged more significantly than larger and well-established plants, which can often withstand some feeding and fully recover. Well-fertilized trees and shrubs are also more attractive to deer than unfertilized ones.

That has a practical side. If you planted this year, those plants need protection first, because a browsed leader on a young tree takes away its main growing tip. See our guide to fall planting for what else a first-winter plant needs. Mature shrubs that lose some tips can usually be left alone, and any ragged stems can be tidied up in spring.

Are there really deer-resistant plants?

Only relatively. MSU's line is that deer-resistant does not mean deer-proof, and that ultimately no plant is safe from a hungry deer. It also says selecting less preferred plants may be the most cost-effective way to prevent damage, and suggests arranging resistant plants around the more preferred ones.

Plants with prickles and spines, tough or leathery leaves, milky sap or strong aromas are often left alone when something better is nearby. That is a planning decision for next season rather than a winter fix. Our list of the best deer-resistant plants for western Montana uses MSU's ratings, and landscaping design is where we can help build that into a yard.

What is the most reliable way to protect a plant this winter?

A physical barrier. MSU says exclusions should be concentrated on critical areas such as gardens and high-value trees, kept as small as possible, and can be temporary or seasonal. MSU's tree guide also recommends trunk guards or tree protectors for vulnerable trunks. For winter, that often means a wire cage around a young tree or shrub, tall enough to cover what you are protecting and held well away from the foliage.

Plan for the snow in your own yard, too. A cage that looks tall in October may be much shorter once snow has packed around it. Set the supports before the ground freezes, because driving a stake into frozen soil is a miserable job, and mark cages near a driveway so they do not get hit: see snow stakes and markers.

Would a fence do the job?

It can, if it is tall enough. MSU says a permanent fence at least 6 feet high may be cost effective for backyard gardens with constant deer problems. University of Minnesota Extension recommends fences at least 8 feet high and strongly built, noting deer can clear up to 12 feet with a running start. Those are different recommendations from different states, so consider your pressure and how much is at stake.

MSU also describes woven-wire fences as expensive and difficult to construct but easy to maintain, and vertical electric fences as effective for moderate to high pressure but needing weekly inspection and voltage checks. Corner posts and braces matter for high-tensile systems. Fencing is a spring or fall project rather than a January one. Our guide to deer and elk fencing covers design, and we build custom fencing across Missoula and the Bitterroot.

Do deer repellents work in winter?

Somewhat, for a while. MSU's general principles are the place to start. Repellents typically only reduce damage, and even the most effective reduced browsing by about 60 percent. They work less well on highly palatable plants, they only work if deer have other food available, and they generally last only one to two weeks before needing reapplication according to label directions.

Some winter results are better. MSU reports research showing putrescent whole egg products protecting plants for up to 13 weeks in winter and three weeks in spring, and dried blood for up to 11 weeks in winter and one week in spring, though other tests found shorter protection for blood. Thiram reduced winter deer browse damage by 43 percent in one study, and capsaicin products at 6.2 percent repelled deer for two weeks, while a 0.062 percent product showed no effect. MSU's overall ranking of the most effective active ingredients is putrescent whole egg solids, ammonium soaps of higher fatty acids and capsaicin at 6.2 percent or more.

Are home remedies legal and effective?

MSU says use of home-remedy products as repellents is illegal, because repellents are pesticides that must be registered with the EPA and the Montana Department of Agriculture. That includes checking that products bought online are registered in Montana: MSU notes that brick and mortar stores in Montana sell only registered products, but online stores may not know. The label is the law.

The results are not impressive, either. MSU cites studies of hair bags reducing damage by 35 percent under moderate feeding, tallow soap bars by 38 percent with protection of an 18-to-36-inch radius, and Milorganite by about 30 percent. In one test, 93 percent of plants treated with garlic at three times the recommended rate were damaged within four days under high deer pressure.

What about scare devices?

Do not expect much. MSU says frightening devices work only for short periods, a few days to weeks, because deer quickly learn there is no real threat. Motion-activated devices do better than timers. Ultrasound has not been shown to frighten deer, research shows green and red lasers are ineffective, and noise devices can annoy neighbors. MSU concludes that compared with repellents, they are significantly less effective.

See do bird scare devices work if you are comparing the same approach for geese or starlings. The pattern of quick habituation is a familiar one.

Can I feed the deer so they leave my shrubs alone?

No. It works against you, and it can be illegal. Montana Code Annotated 87-6-216 says a person may not provide supplemental feed attractants to game animals by purposely or knowingly attracting cloven-hoofed ungulates, bears, mountain lions or wild turkeys, and it provides penalties. The statute has exemptions, including for normal feeding of livestock, normal agricultural practices and cultivating a lawn or garden. This is general information and not legal advice, so ask Montana Fish, Wildlife & Parks or an attorney about your own situation.

Recreational bird feeding is treated separately in that statute, but it is exempt only unless it continues after a prior department warning. Bird feeders can draw other animals as well: University of Minnesota Extension notes that feeders attract voles.

What should you do about browsed plants in spring?

Wait until growth starts, then assess. MSU says large and well-established plants can often withstand some feeding and fully recover, so give them a chance to push new growth before deciding anything. Prune out torn stems, using smooth cuts back to healthy wood. MSU Extension forestry specialist Peter Kolb explains that a smooth cut lets new bark cover a wound much faster than a jagged break.

If a young tree lost its leader or a shrub keeps being eaten to a stump, it may be time to move or replace it, or to protect it more seriously next year. Our dormant pruning and tree services can help, and yard cleanup after the snow melts covers what else to look at.

Who can help protect a landscape from deer?

We can help with the parts that last: fencing, plant selection, pruning and assessing damaged trees. Our ISA Certified Arborist, Justin Johnson (RM-8889A), offers tree health and risk assessments. Through the winter we also run snow and 24-hour storm services for homes across the valley. Call (406) 215-7319 or request a free estimate.

More resources