Garden defense: How to outsmart hungry deer

No garden pest is more destructive than deer. In one night, they can devastate a hosta garden and chew daylilies and impatiens down to the ground.

Keeping them out of yards is nearly impossible. Some experts say fencing has to be 10 feet high to deter them, something that few if any cities allow in residential areas. Healthy deer can clear an 8-foot fence from a standstill.

So all gardeners can do is try to outsmart them. And that isn't easy.

It helps to understand deer. In his excellent book "Deer-Resistant Landscaping," Neil Soderstrom says that on their first visit to a yard, deer will sample almost every plant so they know what they like when they return. They favor things that taste good, especially juicy young plants. Soderstrom says that because deer don't have upper incisors, one marker of their damage is stems that look shredded or ripped.

Many of our best-loved landscape plants, including apple trees, yews, arborvitae, daylilies, hosta, viburnum and hydrangea are on their best-liked list, too. But while a hungry deer will eat almost anything green, some plants have less appeal.

Those plants are called deer-resistant, not deer-proof. Some of them are spiny, sticky, fuzzy, highly scented or even toxic. They include marigolds, lamb's ears, cleome, mints and lavenders, daffodils, ageratum, peonies, most ornamental grasses, goldenrod, Joe Pye weed and yarrow. The University of Minnesota Extension Service has a list of suggested plants in this fact sheet on dealing with deer: http://tinyurl.com/haoz4tt

And Minnesota Master Gardeners have compiled their own list of deer-resistant plants: http://tinyurl.com/hwyfq8w

Repellents, including highly scented bath soaps, human hair clippings and sprayed egg and hot pepper mixes, may work for a while. Most need to be reapplied about every 10 days and after a rain, and deer often ignore repellents once they're used to them. If gardeners are trying to protect edibles, they should choose repellents carefully, reading the labels to make sure they're safe for use on vegetables and fruit.

Commercial hot pepper sprays are sold in garden stores, as are spray or granular repellents made of pig or cow blood. Blood-based repellents tend to last longer on plants but may smell bad, can temporarily turn plants red or brown and are expensive. Some may attract cats or dogs.

Motion detectors that pepper deer with hard sprays of water are a low-impact deterrent. A variety of battery-operated detectors are on the market for about $40 and up. A spiked base allows them to be installed anywhere in your yard. The detectors have sensitivity settings that trigger sprays for animals as small as a rabbit up to large animals like deer. Attached to a hose, the detectors fire a hard spray of water in an arc across the area where the target is detected.

Just be careful to turn the water off during the day, or an innocent gardener who bends over to weed may get very wet!

Not every method to deter deer needs to be expensive. While I don't know of research to back up its effectiveness, some gardeners swear by fishing-line fences.

Gardeners have to experiment to see what works for them. Deer in one area may avoid certain plants, while deer in another location gobble them up.

Soderstrom, for one, found that simple solutions may work much of the time. A 4-foot wire fence planted with tall annuals like cleome or zinnias that are unappealing to deer may block their view of a garden and cause them to turn elsewhere for their meals.

And if all that doesn't work, having a dog scouting the yard is a definite deterrent. But deer like to do their raiding at night, and even dogs deserve a good night's sleep.