The common garden snail and its close relative, the slug, are terrestrial mollusks and generalist feeders, consuming a wide variety of organic matter they encounter. These soft-bodied creatures use a rasp-like mouth structure called a radula to scrape and chew their food. Their presence is confirmed by the irregular holes they leave in foliage and the characteristic silvery, dried mucus trails they deposit as they move. A snail’s diet is heavily influenced by moisture, as they are most active during damp periods and at night to avoid drying out.
Primary Targets in the Garden
Snails and slugs are primarily attracted to plants with high moisture content and a tender, succulent structure, making them easy to consume with their radula. Young seedlings and newly sprouted growth are particularly vulnerable because their tissues have not yet developed the tough, coarse fibers of mature plants. They can quickly consume a small plant down to a nub, preventing it from growing into a mature specimen.
Leafy vegetables are high on their menu, with common targets including lettuce, cabbage, and tender herbs like basil. Ornamentals with soft foliage, such as hostas, dahlias, and delphiniums, are also frequently damaged. Snails target soft fruits that ripen close to the ground, with strawberries and low-hanging tomatoes being common victims. The damage often appears as large, smooth-edged holes in the leaves or gouged-out sections of the fruit.
Secondary and Non-Plant Food Sources
While living plants are the source of damage most noticed by gardeners, snails and slugs are not strictly herbivores and rely heavily on detritus for their nutritional needs. They play a role in the garden ecosystem by consuming decaying organic matter, such as dead leaves, withered flowers, and other plant debris. By breaking down this material, they help recycle nutrients back into the soil.
Fungi and algae are also consistent parts of their diet, as these are often abundant in the cool, damp environments where the mollusks thrive. Some species are omnivorous scavengers, occasionally consuming carrion, dead insects, or even other snails and slugs. Snails have a specific need for calcium to maintain and grow their protective shells, which they acquire by consuming small amounts of soil, grit, or mineral-rich materials like crushed eggshells.
What Snails Generally Avoid
Snails and slugs bypass many plants that have developed natural defenses against grazing, focusing instead on easier targets. Plants with highly scented foliage or strong tastes, such as many herbs, are generally avoided. Aromatic plants like rosemary, sage, fennel, and lavender are often left untouched because of their strong essential oils.
The physical structure of a plant’s leaves also determines its palatability. Plants with tough, leathery, or waxy leaves, such as ornamental grasses and woody shrubs, are resistant to the scraping action of the radula. Similarly, foliage covered in fine hairs or a fuzzy texture, like lamb’s ears or some geraniums, makes movement and feeding difficult. Some plants, like foxglove and euphorbia, contain toxic or repellent compounds, such as milky latex sap, which deters feeding.