Six must-know prevention tips. By Sean McNamara

The deer population across the country is exploding. While the sight of a deer in your backyard is exciting, the damage they do to your plants is not. Deer damage, especially during the winter months, is severe and expensive. Protecting customers’ landscapes from winter deer damage has become big business and deer damage prevention is a great way to attract and keep satisfied customers.

Growing up in Connecticut in the 1970s, the sight of a deer was such a rare event that you would stop your car and get out to take a closer look. Today there are so many deer you have to swerve your car to avoid hitting them. The same is true in many suburbs across the country where you may see eight to 15 deer at a time roaming through the neighborhood.

A hundred years ago, the outer suburbs of major cities were mostly farmland and cleared of trees, and there were very few deer. But over time the farms receded and the land was turned over to housing developments. Some of the land was set aside for open space and the woods have returned. Today the woods have matured and provide food and cover for deer. It is an excellent habitat with few predators. Across the country suburban landscapers and plant care companies have struggled to protect their customers’ expensive landscaping from hungry deer.

It can be frustrating when a deer munches on your hostas or vegetables, but when they turn your $7,000 arborvitae hedge into a line of popsicle plants like something out of a Dr. Seuss book, it’s downright maddening.

Deer do their most destructive damage from Thanksgiving to April. The winter of 2013-2014 was among the worst in recent memory. Snow, ice and freezing temperatures took a toll on landscape plants. However, in many suburbs it was not the cold that did the greatest damage, it was hungry deer.

Stopping winter deer damage is a great way to give value to your customers. Here are six things you need you know to take advantage of this growing plant care niche.

1. Deer will only eat evergreen trees and shrubs during winter months.

There is no need to protect evergreens during the growing season. But in the autumn as deciduous shrubs lose their leaves, food becomes scarce, and in the depths of winter deer diets change to include arborvitae, rhododendron, azalea and hollies. Plants that are “deer resistant” in one area may not be in another. Where deer populations are high, the list of deer-resistant plants is short.

2. Fences aren’t always the answer.

A deer can easily jump over a 6- to 8-foot fence. A true deer fence should be 10 to 12 feet high and should be monitored and maintained throughout the year. A fallen tree can take out a section of fence and give deer access to a protected landscape. In many communities, zoning laws may restrict the size and type of fencing allowed.

3. Most deer repellents don’t work during the winter.

Traditional deer repellents typically use offensive smells to keep deer away from potential food. But during winter months freezing temperatures suppress odor. During the winter you need to use a strong taste deterrent such as thiram.

4. Spray repellents need to be long lasting.

It is near impossible to apply liquid repellents during winter’s freezing temperatures, wind, snow and ice. A deer repellent that needs to be reapplied every month is just not practical. For a successful deer repellent program, a long-lasting thiram-based product with a superior sticking agent must be used.

5. Don’t protect plants the deer don’t eat.

Homeowners often plant shrubs they know that deer won’t eat, such as boxwood and andromeda. They don’t want to pay you to protect deer-resistant plants. Educate yourself and educate your customers: find out what plants the deer are eating in your area and avoid spraying the plants they leave alone.

6. Watch the acorn masts.

Deer and other critters eat acorns and nuts in the fall to load up on carbohydrates. When acorns are plentiful, deer are less likely to decimate evergreens that winter. However, when acorn masts are light, deer will run out of fat reserves and feed heavily on evergreen trees and shrubs in order to survive the winter.