Deer damage to woody ornamentals

How to stop serving your fresh produce to the deer herd.

Deer damage. Photo credit: Paul Bolstad, University of Minnesota,
Deer damage. Photo credit: Paul Bolstad, University of Minnesota,

As winter approaches, many four-legged furry critters are taking a serious look at your landscaping for winter sustenance. This diverse population of mammals includes deer, rabbits and voles. Others like skunks, raccoons, woodchucks, moles and opossums are either napping the winter away or are not interested in the landscaping as food items. Annuals and perennials are done for the year and unless a vole is digging around perennials and eating the crowns of the plants, there is not too much to feed on. Michigan State University Extension horticulture educators and Master Gardener hotlines receive calls in the spring about tree and shrub damage, but by that time, it’s too late.

Of the animals interested in your woody landscaping, deer are the largest in size. They have the ability to damage higher into trees and shrubs because of their height and can stand on their hind legs to add as much as 4 feet to what they can reach. During the winter, a deer’s diet consists of high fiber woody plant material. Deer are browsers, not grazers. They move from place to place, snipping and snapping buds and ends off branches and peeling tender bark. They can paw through the snow to find tuberous roots and mosses.

Two factors contribute to deer in peoples’ yards: the deer herds are substantial in many areas in Michigan, and people often clear understory shrubs and trees in wooded areas. This is considered ideal deer browse, but now they must look elsewhere because that material has been removed.

To protect trees and shrubs, it may be necessary to “fence off” deer so they can’t prune important landscape plants. Spray-on repellants work during summer because they have a bad odor. Those same repellants in the winter do not keep their unpleasant qualities in the cold air. It is necessary to find other ways of protecting trees and shrubs. Fences can be the traditional vertical barrier that is secured to posts, or you might be able to use the same fencing material in a different manner.

If a fence is installed in the usual manner, wooden or metal posts are sunk into the ground and some kind of wire fencing is secured to the posts. If the fencing is installed too close to the trees or shrubs, the hungry deer just pushes into the fence and feeds. Always put the fencing on the outside of the posts so the posts help to strengthen the fence. The fence should not be placed too close to the plants. A gap of 3 or 4 feet should work. If the fence is too close, using a single electric hot wire with insulators at the very top of the fence will put a jolting end to fence-leaning.

Another possibility is the same fencing material used horizontally. Place concrete blocks on the ground in a zigzag pattern surrounding what needs to be protected. Sit them on their ends so they are 16 inches tall. Unroll woven wire or other fencing that is at least 4 feet tall, placing it flat on the top of the cement blocks. When the fencing is complete, a deer will not attempt to step into the fencing and possibly get its legs entangled. The fence is placed 2 or 3 feet from the tree to be protected. Make sure corners are closed so no deer can find a gap in your Great Horizontal Wall. To make the fence more noticeable, wire a few jingle bells to it so it makes noise if bumped. Smart gardeners might consider this value-added idea.

In the spring, don’t be too hasty to remove the fence. March to the middle of April is too early. Growing plants begin to be tastier in May and until that time, deer are sticking to their high fiber diet. That could include your woody ornamentals. Then, roll up you fencing and put the concrete blocks away for another season.

For more information on protecting your landscape or garden year-round from deer, see "Discouraging deer year-round in your yard: Facts versus fantasies."  

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