Garter snakes (Thamnophis genus) are non-venomous and generally harmless, often benefiting gardens by preying on common pests. However, their presence near homes often prompts homeowners to seek non-lethal deterrence methods. Successfully repelling garter snakes requires a multi-faceted approach focused on eliminating attractants and installing physical barriers. This article provides practical strategies for modifying the environment, implementing structural exclusion, and evaluating chemical treatments.
Modifying the Habitat to Eliminate Attractants
The most effective long-term method for deterring garter snakes is removing the resources that attract them: readily available food sources and secure shelter. By eliminating these fundamental requirements, the habitat becomes undesirable, prompting the snakes to move elsewhere.
A primary attractant is the snake’s diet, which includes slugs, earthworms, leeches, small amphibians, and sometimes rodents. Controlling these prey items directly reduces the incentive for snakes to remain on the property. Water features, such as decorative ponds or constantly damp areas, are particularly attractive because they draw in amphibians, a favorite food source.
Proactively address any rodent issues near the home, as rodents serve as a substantial food source for larger snakes. Reducing dampness and eliminating standing water also lowers the concentration of preferred prey, such as amphibians, which are drawn to moisture.
Garter snakes also seek out shelter for protection from predators and for thermoregulation, especially for basking or overwintering. Woodpiles, rock piles, compost heaps, and dense vegetation, particularly near foundations, provide ideal hiding spots. Removing these debris piles and storing firewood on raised racks away from structures eliminates these secure retreats.
Keeping the lawn mowed to a consistently short height is also recommended, especially around the perimeter of the home and garden. Tall grass provides cover that snakes use to move undetected and to hide while basking. Eliminating this cover makes the area feel exposed and less safe for the snake, encouraging it to seek refuge in a more secluded location.
Implementing Physical Barriers and Exclusion
Structural modifications are necessary to prevent garter snakes from gaining entry into specific areas, such as homes, sheds, or enclosed gardens. Since garter snakes are slender and highly capable of maneuvering through small spaces, exclusion efforts must be meticulous and use materials specifically designed for this purpose. The first line of defense is sealing any openings in the building’s foundation.
Garter snakes can easily squeeze through gaps as small as a quarter-inch, meaning that any crack, pipe entry point, or utility opening must be thoroughly inspected and sealed. Foundation cracks should be filled with mortar or a heavy-duty sealant, while larger openings, such as vents, should be covered with 1/4-inch hardware cloth. The 1/4-inch mesh size is critical to prevent the entry of even juvenile snakes.
This sealing work is best performed during the summer months when garter snakes are active outside and not denning within the foundation for the winter. Sealing a den entrance while snakes are inside can result in them being forced into the living space or dying within the structure, leading to odor issues. All utility conduits and uneven door thresholds must also be secured to eliminate potential entryways.
For larger perimeter exclusion, a snake-specific fence can be constructed using galvanized hardware cloth with a 1/4-inch mesh size. A successful barrier should be at least three feet high to prevent climbing and must be installed correctly at the base. The bottom edge of the fence material should be buried four to six inches into the soil to prevent burrowing underneath.
To maximize the fence’s effectiveness against climbing, the barrier should be angled outward from the enclosure at approximately a 30-degree angle. This outward angle is designed to redirect the snake’s upward movement back onto the ground. Gates must be equally protected and kept closed, as snakes will travel along the fence line until they find the path of least resistance.
Evaluating Scent-Based and Chemical Repellents
Scent-based and chemical repellents are often marketed as simple solutions, but their efficacy against garter snakes is limited and temporary. These products attempt to interfere with the snake’s sophisticated sense of smell. For repellents to be effective, they must have a strong, persistent odor.
Commercial snake repellents often contain active ingredients like sulfur or a combination of essential oils, such as cinnamon, clove, and cedarwood. These substances are applied in a band around the area to be protected, theoretically creating an olfactory barrier the snake will not cross. However, the odor dissipates quickly, especially after heavy rain or irrigation, requiring frequent reapplication.
One common, yet strongly discouraged, home remedy is the use of mothballs, which contain the chemical naphthalene or paradichlorobenzene. These chemicals are ineffective against snakes because they are not toxic to reptiles in the same way they are to insects. Furthermore, mothballs are toxic to humans and pets, and using them outdoors is considered an environmental hazard that violates product labeling.
Essential oils are often cited as natural deterrents, but scientific data supporting their long-term effectiveness remains limited. While their strong aroma may cause a snake to briefly detour, they do not provide the consistent, reliable exclusion needed for permanent control. Any applied substance should only be used outside the home, and its temporary nature must be factored into the overall deterrence strategy.