Considered one of the worst garden pests, slugs are brown- to gray-colored mollusks that feed on a wide range of plants, causing irregular holes with smooth margins in leaves, blooms and stems. Slugs typically feed on young plant tissue at night or on overcast days, preferring to spend sunny days in moist, shady environments. You can effectively kill slugs using various homemade traps, solutions and barriers.
Slugs are attracted to the smell of fermenting malt and yeast in beer. If you don't have any beer on hand, use straight grape juice or combine 2 teaspoons of baking yeast and 8 ounces of water to make a liquid solution. Bury a pie pan, plastic butter tub or other shallow container with the edges even at the soil line. Fill the container to within 1 inch of the rim with your choice of liquid. Slugs will crawl into the container and drown. Replenish the liquid every three days, but remove slug carcasses every morning so the trap stays clean. Traps only have about a 3-foot range, so place them accordingly throughout your yard or garden to control slug populations.
Ammonia sprays perform well as molluscicides, but the solution must make direct contact with the slugs in order to work. In a small spray bottle, combine 3 ounces household ammonia with 16 ounces water. Take the bottle out to your garden during the cool evening hours and spray all feeding slugs you can find. Wait 24 to 72 hours to check for slug activity. If you spot the slimy pests still feeding on plants, make a solution containing equal parts household ammonia and water for some extra slug-killing oomph. One benefit of spraying with ammonia is that it turns into nitrogen that plants can use for food. One drawback is that ammonia can injure sensitive plant foliage. Test the solution on a small section of leaves and wait at least 24 hours to check for damage. Treat your entire plant if no burning occurs.
Garlic oil sprays cause slugs to secrete an excess of mucus. In time, the mucus overproduction causes the mollusks to dry out, shrivel up and die. Make your own spray by soaking 4 cloves of minced garlic in 1 tablespoon of mineral oil for about 24 hours. After straining the solution to remove the garlic pieces, pour it into 1 pint of water and add 1 teaspoon of liquid dish soap. Keep this garlic oil concentrate in your refrigerator until you're ready to spray. Make a garlic spray by mixing 2 tablespoons of the garlic oil concentrate and 1 pint of water in a handheld spray bottle. Wait until the sun goes down to apply the solution to the tops and undersides of leaves. Apply garlic spray every 24 to 72 hours until slugs no longer feed on your plants. Reapply immediately after a rain since the water washes the oily solution from the foliage. Test the solution on a single leaf before treating an entire plant.
Making a barrier around plants with an abrasive substance helps kill off slimy slugs by cutting up their bellies when they crawl across it. The lacerations cause the pests to lose moisture, which makes them dry up and die. Dry wood ashes, diatomaceous earth, fine sand, pine needles and crushed eggshells all have gritty, sharp edges that can cause slugs bodily harm. Apply your chosen material in swaths about 3 inches wide and 1 inch high around valued plants, but keep the substance from touching the plant bases. Renew barriers after watering or rainfall because moisture makes the materials less effective,
A Few Considerations
Even homemade pesticides can irritate sensitive skin and eyes with direct contact. Protect yourself from accidental exposure by wearing waterproof gloves, goggles, a face mask and long sleeves when applying barriers or mixing and spraying solutions. As always, keep pets and family members safe by not allowing them near treated plants until liquid solutions dry or dusts settle. Treat plants on days with little to no wind to keep solutions from drifting out of the designated treatment area.