Deer, Mice, and Bugs, Oh My!

Outsmarting Nature’s Nibblers

It is often said in the field of Landscape Architecture that when it comes to plants, clients request three things: low maintenance, year-round blooms, and deer resistance. The obvious solution to this wish list is a stunning palette of native plastic plants, perfectly complemented by a synthetic turf lawn. If, by some chance, you read that sentence and thought, "Amazing! Where can I purchase this landscape?", I urge you to stop reading and call your local football field installer immediately.

Let us begin with the premise that outdoor spaces are ecosystems, composed of countless living organisms that interact with everything in their physical environment. Sometimes, the organisms in the environment are songbirds and flowers—elements everyone loves to see and experience. Other times, the flora and fauna are less welcome: deer that browse on flowers, small mammals that infiltrate homes, bugs that chew up foliage, and diseases that kill plants.

The environmentally sensitive way to manage pests is by using "Integrated Pest Management", a process that understands that there is no one-size-fits-all approach to maintaining a healthy landscape. Even small residential gardens are dynamic living  environments that require a thoughtful and dynamic approach to maintenance. The following writing will help you explore the challenges you may be facing in your garden, and outline properly weighted actions you can take to mitigate these issues.

Deer

Simply put, White-Tailed Deer are difficult. Deer-resistant plants are at best less appetizing for deer, but any seasoned gardener will tell you that there is nothing the hoofed menaces won’t eat. Exotic plants such as hydrangeas are often more appetizing than others. Native plants are sometimes less of a delicacy and can also occasionally survive better after a mild grazing. Historically, people have turned to chemical sprays to keep deer off of plants. Chemical deer sprays can not only be harmful for humans, but wash off into the local rivers and bioaccumulate into animals up the food chain. If you care about your family, neighbors and environment, avoiding chemicals is a must. 

If deer eat everything, and chemical warfare is worse than feeding the aggressors, what are the safe options? Luckily there are a gradient of solutions to provide a defense against these attackers. The most effective option is to install a fence. For deer, the fencing needs to be 8 feet tall in order to fully stop them.  Many town codes will not allow for such tall fencing, and aesthetically speaking it can make a property feel enclosed and unwelcoming.  Installing a 6 foot tall fence with a 2’ deer wire on top can act as a barrier for the deer while providing open air above the fence.

Peppermint oil sprayed in small amounts at the garden bed can sometimes succeed at preventing deer from entering a garden bed without causing issues to the surrounding environment. (1)  Other organic sprays in extreme moderation can also provide some degree of relief. It is important to note that even organic sprays have a range to the damage they can cause. The Organic Materials Review Institute provides guidance for which organics are safe.  

Deer tend to dislike plants such as mint, lavender, thyme, alliums, and marigolds, to name a few.  They don’t love grasses and sedges, which are also tolerant to the occasional grazing if it does occur. Adding these plants to the exterior of a garden bed can sometimes lead to deer avoiding the plantings altogether. Mixing deer resistant plants along with a biodiverse planting, can have the effect of slowing down the grazing, leading to a reduction in damage.  

Structural protection is important, especially if the garden does not have a fence and is in the first year of growth. Deer are fond of young plants and new growth, and will eat young plants that they would otherwise avoid when fully grown. Netting is one option that can help protect the plants from being chewed or pulled up. The netting can be staked around garden beds, draped over individual or multiple plants, or suspended above plants. It is important to secure netting into the ground or along the posts, and to allow for plant growth and prevent pressure on the plants. Netting can also double as a deterrent for other garden pests.

(1) Cirigliano, Joy, “HELP: Habitat and Ecosystems Land Pro”

Rodents

Similar to deer, organic sprays and netting can be effective tools against rodents such as mice, rats, chipmunks, and squirrels.  Many pesticides should be avoided when removing rodents, particularly anticoagulants which are used to kill rodents. Anticoagulants are blood thinners, which cause the animals to bleed out. Not only is this a cruel way to kill an animal, but is dangerous for birds who will eat the injured animal and sometimes die from the poison. Instead of thinking about how to kill the animals, the easiest way is to prevent the issue altogether.

While it may be a common aesthetic choice to plant shrubs to cover the foundation of a house, this design choice will lead rodents closer to the home as they search for food and shelter. A design intervention that can be used to avoid foundation plantings, is to simply move plants away from the foundation of the house. When animals are farther out in the environment, the chance of them finding their way into a home is low. Avoid piling wood, and planting grasses or low woody shrubs near the foundation to reduce the risk of rodents from coming into your home. If plants are unavoidable along the foundation, similar to deer, rodents tend to dislike mint, lavender, thyme, the allium family, and marigolds.

Insects

Insects are very specific creatures; they often feed and/or live on only one type of plant. This specialism allows insect treatment to be focused. Common chemical sprays may kill the targeted insect but also harm other beneficial insects that are part of the ecosystem. There is no need to attack the entire ecosystem when the issue is so specific.

Alternatives to chemicals include botanicals, which are plant-derived toxins that target specific insects. Botanicals such as neem, pyrethrins, and diatomaceous earth can be effective. Botanicals need to be applied correctly to ensure they are safe for the surrounding environment and the targeted insect. Microbials, which are microorganisms, can also effectively stop specific insects through targeted attacks. Full-sized insects, such as ladybugs, can be used to control aphid and mite outbreaks. (2) There are many ways to control insects and ultimately management needs to be catered to each plant and insect.

(2) Cirigliano, Joy, “HELP: Habitat and Ecosystems Land Pro”

In Conclusion & Beyond

The spray-and-pray chemical blankets of the past are dangerous and ineffective. Integrated Pest Management is key to getting pests under control in ways that benefit both the environment and people. Always remember that if one technique doesn’t work, there is always another. Deer can destroy a garden, rodents can infiltrate a home, and insects can chew away at beautiful foliage. Don’t be discouraged. At the end of the day, we are all part of our ecosystems, and part of the joy of ecology is what you learn along the way.