Finding unexpected holes in flower beds is frustrating for any gardener. Damage to bulbs, roots, and soil structure is often the first sign that local wildlife is excavating the property. Solving this problem requires identifying the animal responsible, as different species have distinct digging styles and motivations. Learning to read the signs left behind in the soil allows you to pinpoint the culprit and apply a targeted, effective strategy.
Deciphering the Damage: Identifying the Culprit
The size, shape, and depth of the hole provide the most reliable clues for identification. Small, conical holes scattered across the bed are a classic sign of an animal foraging for insects just beneath the soil surface. Skunks are the most frequent culprits, creating neat, cone-shaped depressions one to three inches across as they root out beetle larvae (grubs) or earthworms. These foraging holes are numerous and shallow, indicating a systematic search for a protein-rich meal.
Small, shallow holes are also left by squirrels and chipmunks, though their purpose is distinct. Squirrels quickly dig and re-bury nuts or seeds, leaving behind small, two-inch-wide depressions that are not very deep. Chipmunks create silver dollar-sized holes, but their burrows are cleanly excavated with little displaced soil around the entrance, as they carry the dirt away in their cheek pouches. The presence of these small caching holes is often more noticeable in the autumn when food storage activity peaks.
A different type of damage involves broad, shallow scrapes and larger areas of disturbed soil. Raccoons are known for this type of excavation, often rolling back newly laid sod or tearing up sections of a flower bed in a search for grubs or other invertebrates. This disturbance looks less like a neat hole and more like a messy churning of the soil, sometimes revealing paw prints that resemble miniature human hands. These nocturnal foragers possess the strength and curiosity to cause extensive surface-level damage.
When the damage involves a large, deep hole leading into a defined tunnel, the culprit is likely a burrowing animal seeking shelter. Groundhogs (woodchucks) create substantial burrows with entrances measuring 10 to 12 inches in diameter. Their tunnels are extensive, sometimes running up to 30 feet long and three to six feet deep, often located near structures like sheds or dense shrubbery for added security. Voles, in contrast, create much smaller burrows, with multiple flat entrance holes only one to two inches wide, connected by narrow, visible surface runways through the vegetation.
Understanding the Motivation for Digging
The primary reason animals dig is related to survival, falling into three main categories: foraging for food, establishing shelter, or storing resources. Many animals disturb flower beds while targeting the rich concentration of invertebrate life found in garden soil. Skunks and raccoons are motivated by a seasonal desire to consume insect larvae, such as Japanese beetle grubs, which live just below the root line. The abundance of these protein sources turns a flower bed into an easy feeding ground.
Other species dig specifically to access or cache plant matter, particularly during periods of resource scarcity. Herbivores like voles feed on plant roots and bulbs, often pulling the material into their shallow tunnel systems from below. Squirrels are driven by an instinct to store food for later consumption, burying nuts and seeds in the soft soil of flower beds. This caching behavior is a survival strategy.
The third motivation is the need for secure, long-term shelter. Larger animals like groundhogs create deep, complex tunnel systems for nesting, raising young, and overwintering. These deep burrows offer protection from predators and the elements. The location of the burrow is usually chosen for structural stability and overhead cover, often under a deck, patio, or foundation.
Practical Strategies for Deterrence
Effective deterrence relies on addressing the specific motivation and behavior of the identified animal. If the damage is caused by foraging animals like skunks or raccoons, the most direct solution is to reduce the primary food source. This can involve applying products such as beneficial nematodes, which are microscopic organisms that naturally parasitize and eliminate soil-dwelling pests like grubs. Removing this concentrated food source encourages the animals to forage elsewhere.
For animals that burrow for shelter, physical exclusion methods offer a more permanent solution. To deter groundhogs and similar deep burrowers, install a fence that extends at least 10 to 12 inches below the soil line and is bent outward at a 90-degree angle to prevent tunneling underneath. For protecting specific plantings from voles or squirrels, hardware cloth or chicken wire can be placed directly over newly planted bulbs or seeds before covering them with soil. This creates a physical barrier that prevents access to the food source.
Cultural and environmental modifications can also make the garden less appealing for all species. Removing attractants, such as securing compost bins and pet food left outdoors, reduces the incentive for nocturnal visitors. Using materials like coarse gravel or sharp mulch instead of soft organic mulch can make the area physically uncomfortable for animals to dig in. Deploying motion-activated deterrents, such as sprinklers, can effectively startle and condition animals to avoid the area.