Gardeners often find their newly planted tulip bulbs vanished or their emerging flowers chewed down. The immediate assumption points to the mole, known for its prominent mounds and tunnels. However, the mole is almost certainly not the direct culprit consuming the tulips. Understanding the distinct habits of the small mammals operating beneath the surface is the first step toward safeguarding a spring bloom.
The Mole’s True Diet
The mole is fundamentally an insectivore, meaning its diet consists almost entirely of invertebrates found in the soil. Moles possess a high metabolism, requiring them to consume 70 to 100 percent of their body weight daily, which drives their constant tunneling for food. Their primary food source is the earthworm, supplemented by grubs, beetle larvae, and other insects.
These specialized hunters use sensitive snouts and powerful forelimbs to capture prey within their complex tunnel networks. While moles may occasionally ingest small amounts of plant material, they cannot thrive on a diet of tulip bulbs. The connection between moles and missing bulbs is indirect, as their extensive tunnels often provide protected travel routes for the true bulb-eaters.
Identifying the True Bulb Eaters
The actual perpetrators of tulip bulb consumption are typically voles, which are small rodents. Unlike moles, voles are herbivores with a diet focused on plant roots, seeds, stems, and tulip bulbs. Voles often leave behind distinct clues that differentiate their damage from the mole’s tunneling activity.
Voles gnaw on the bulbs, frequently leaving only empty, hollowed-out husks behind. They create numerous shallow tunnels and small, open burrow entrances, often near the base of shrubs or trees, unlike the large mounds associated with moles. Mice and squirrels are common culprits. Squirrels generally dig up bulbs and leave them partially chewed on the surface, while voles and mice consume them completely underground.
Strategies for Protecting Tulip Bulbs
Protecting bulbs requires a strategy that addresses the specific habits of vegetarian pests, primarily voles and mice. One effective method is using physical barriers to prevent rodents from reaching the bulb. Gardeners can create underground cages or baskets using half-inch mesh hardware cloth, a sturdy wire material that allows roots and shoots to pass through while blocking pests.
Another approach involves adding coarse, unappealing material to the planting hole to deter burrowing rodents. Mixing materials like crushed oyster shells, gravel, or coarse granite grit directly into the soil surrounding the bulbs creates a sharp, unpleasant barrier that voles and mice avoid. This leverages the rodent’s aversion to digging through abrasive textures.
Natural repellents can also be integrated into the planting process. Castor oil-based products, applied as a granular barrier, repel burrowing rodents due to their strong odor. Additionally, planting bulbs that voles naturally avoid, such as daffodils, alliums, or Fritillaria, among the vulnerable tulips serves as a natural deterrent. The chemical compounds in these bulbs are unappetizing to the pests.