Gophers are subterranean garden pests whose destructive tunneling habits lead many gardeners to seek natural deterrents. These rodents primarily forage underground, often causing extensive damage by consuming the roots and bulbs of plants. The quest for a safe, natural defense often brings up the question of whether the strong scent of onions makes them a safe crop or a potential defense against gopher activity.
Primary Gopher Dietary Preferences
Gophers are strictly herbivorous, foraging for plant material almost constantly. Their primary food sources are the high-calorie, starchy parts of plants found beneath the soil surface, such as roots, rhizomes, and fleshy tubers. The act of tunneling itself is intrinsically linked to their foraging, as their burrow systems serve as underground highways to access these preferred foods. They are particularly attracted to succulent tap roots and bulbs, which offer a dense source of energy. Common agricultural crops like alfalfa, carrots, and sweet potatoes are favorites due to their substantial root systems. While they spend most of their time below ground, gophers will occasionally pull above-ground vegetation, like grasses and shoots, down into their tunnels for consumption or storage.
The Direct Answer: Consumption of Onion Plants
Gophers avoid consuming the bulbs and roots of plants in the Allium family, which includes onions, garlic, and chives. This avoidance is directly linked to the potent chemical compounds produced by these plants, which are aversive to the gopher’s sensitive sense of smell and taste. The distinct, pungent odor and taste are caused by volatile sulfur-containing compounds, such as propanethial S-oxide, which is responsible for the tear-inducing fumes. When an onion is damaged, enzymes rapidly produce these sulfur compounds, creating a powerful natural defense mechanism. While an occasional gopher might chew on a stray root near a tunnel, they rarely ingest the bulb itself.
Strategic Use of Onions in Gopher Control
The natural aversion gophers have to the strong scent of onions can be strategically utilized in garden pest management. Gardeners can employ companion planting by placing onions or other Allium species directly alongside more vulnerable, high-value crops. Planting a barrier of onions acts as a buffer zone, surrounding the desired plants with a scent the gophers prefer to avoid. Planting a dense border of onions or garlic around the edge of a garden bed establishes a repellent boundary that discourages gophers from tunneling into the protected area. Gardeners can also take advantage of onion scraps by placing cut bulbs or trimmings directly into active gopher tunnels. The concentrated, released sulfur fumes can make the burrow system temporarily uninhabitable, encouraging the gophers to relocate their activities elsewhere.