Ornamental onion, commonly known as allium, is a popular choice for gardeners seeking vibrant, globe-shaped flowers in the spring. A frequent concern when planting these bulbs is the local squirrel population, which is notorious for digging up newly planted material. Squirrels generally do not consume allium bulbs, as these animals actively avoid eating them. This protective quality is due to the plant’s natural defense mechanisms, making alliums suitable for gardens where rodents are present.
The Direct Answer: Alliums as Natural Deterrents
Squirrels avoid allium bulbs due to the plant’s unique chemistry, a trait shared with relatives like garlic, chives, and onions. Alliums contain pungent, sulfur-rich compounds released when the bulb tissue is damaged or chewed. These compounds produce a sharp, acrid taste and odor highly unappealing to many mammals, including squirrels. The powerful scent acts as an instinctive warning sign, signaling that the bulb is not a palatable food source. This chemical defense mechanism places alliums in the category of “squirrel-resistant” bulbs.
Understanding Squirrel Digging Behavior
Gardeners often find allium bulbs unearthed, which leads to the mistaken belief that squirrels are consuming them. This disturbance results from the squirrel’s natural caching behavior. In the fall, squirrels bury nuts and seeds for winter, often using freshly disturbed soil as convenient spots for caching or searching for previously buried food. The smell of a newly turned garden bed attracts exploratory digging. A squirrel may accidentally unearth an allium bulb while attempting to bury a nut or investigate the loose soil. They quickly abandon the bulb due to its unpleasant taste and odor. The resulting mess of displaced soil and exposed bulbs is an incidental consequence of their foraging and burying habits, not a sign of consumption.
Protecting Your Bulbs from Disturbance
Protecting allium bulbs focuses on preventing the initial digging, as squirrels are not motivated to eat the bulb itself.
Physical Barriers
One effective method involves creating a physical barrier over the planting area. Laying chicken wire or hardware cloth flat over the soil surface after planting prevents squirrels from scratching down to the bulb. The mesh should be secured with landscape staples and then lightly covered with mulch or soil to hide it. Applying a thick layer of heavy mulch, such as gravel or crushed stone, can also act as a physical deterrent that is too difficult for a squirrel to move.
Scent and Taste Repellents
Another strategy involves using scent or taste repellents applied to the soil surface. Sprinkling cayenne pepper, crushed chili flakes, or a commercially available granular repellent over the planted area makes the soil unpleasant for squirrels to manipulate. These applications mask the scent of the fresh soil and provide a mild, irritating taste that discourages further digging.
Bulbs Squirrels Typically Consume
Squirrels find certain common garden varieties highly palatable. The bulbs most frequently targeted for consumption are tulips and crocuses, which are rich in starches. These starchy bulbs are a significant source of energy and fat, making them attractive to squirrels foraging during the autumn months. Other bulbs are generally avoided, but for different reasons than alliums. Daffodils and snowdrops contain toxic alkaloids, which rodents instinctively recognize and avoid. Grape hyacinths (Muscari) are also typically left alone. By selecting bulbs like alliums and daffodils, gardeners can create a spring display that is naturally less appealing to hungry wildlife.