Snails and slugs can destroy a garden faster than just about anything, so it’s very important for gardeners to understand their habits in order to control them. Snails and slugs are both mollusks, and very similar to each other; the big difference is that snails have shells. Both move by gliding along a muscle that secretes mucus along the way. That dried mucus is what we call the slime trail.
Snails and slugs shun sunlight, feeding mostly at night and on overcast days. You can recognize slug or snail damage by the irregular holes with smooth margins, especially on seedlings. They will also feed on ripening fruit that’s close to the ground, like strawberries, squash, and tomatoes.
Getting Rid of Snails and Slugs
When they are not feeding, slugs and snails hide under boards, plant debris, ground covers, and branches. Keep your mulch no thicker than three inches deep, and don’t use big wood chips because the pests can hide under them. Eliminating as many of the hiding places as possible is the first step toward keeping the pests out of your garden.
Slugs and snails like moisture. Use drip irrigation instead of overhead sprinklers to eliminate excess water around your plants, making the area less attractive to these garden pests. Water in the morning so plants will be dry by evening when the slugs and snails come out. To increase air circulation and drying, prune lower leaves of garden plants and stake plants like tomatoes instead of letting them trail on the ground.
As much as possible choose plants that slugs and snails don’t favor. Seedlings and succulent plants are particularly susceptible to slug and snail damage. Beans, marigolds, lettuce, hosta, and basil are favorites. However, plants with stiff leaves and fragrant leaves—lavender, mint, and scented geraniums, for example—resist these pests.
Handpicking can be effective if done daily. Drop the slugs and snails into a pail of soapy water and empty the pail onto your compost pile. You can also trap snails by creating hiding places with boards, flowerpots, or inverted melon rinds and collecting them in the early morning. Beer in shallow pans sunken throughout the garden attracts slugs and snails, which drown in the liquid.
Gardeners report varying results with slug and snail baits. Iron phosphate is one of the most effective and least toxic of the commercial baits. Remember to read labels carefully before buying any chemicals to use your garden. Use baits in combination with the methods described above for successful management.
Want to learn more on snails and slugs?
Brown Garden Snail. From Oregon State University, this site focuses on the brown garden snail.
Snail and Slug Control. The University of California’s Integrated Pest Management (IPM) approach to slug and snail control.
Slugs in Home Gardens. Good pictures of slug damage from the University of Minnesota Extension.