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Here Are Your Options with Slugs

This is slightly off the lawn topic, since slugs are not a major pest of turfgrass. Given the spring and summer we’ve had in the Northeast, though, the subject of what to do about slugs comes up just about every day. So what do you do? Here are a few ideas:

With excess moisture slugs can appear in a moment’s notice. The absolute worst thing you can do is head to the garden center for commercially available baits that contain metaldehyde — an ingredient that’s acutely toxic to dogs and other mammals. Classified as “moderately toxic” by the World Health Organization, metaldehyde is the active ingredient in a wide range of products including: Antimilice, Ariotox, Cekumeta, Deadline, Halizan, Limatox, Limeol, Meta, Metason, Mifaslug, Namekil, Slug Death, Slug Fest, Slugit and Slug-Tox. The good news is that gardeners can employ all sorts of safe techniques for keeping slug damage to a minimum. Here are just a few:

1) WATCH YOUR WATERING — While we can’t do anything about the rain, we can adjust our own watering schedule. Slugs do most damage in the evening and at night and the drier we can keep the plants and soil, the better. If you water in the morning the surface soil will be dry by evening on most sunny days. This one change can greatly reduce slug damage.

2) MULCH PROPERLY — What you place around your plants can significantly alter their crawling habits. Finely ground bark, for example, won’t deter them a bit and may, in fact, encourage them by giving them plenty of places to hide on the warm, sunny days when they will look for cover.
Fresh seaweed, if you can get it, is coated with salt and the slugs will stay away. Even as the seaweed dries it becomes coarse and will discourage slug travel. A three- or four-inch coating — around the plants but not touching the stem — is recommended.
Buckwheat hulls, though more expensive than most other mulches, will also work. The slugs don’t like the consistency of the lightweight seed coatings and will stay away.
Some folks don’t mulch at all in the spring while the ground is already moist, figuring that the mulch will trap the excess moisture that creates ideal slug conditions. When the soil begins to dry in mid-summer, it may be safer to apply your bark, pine needles, straw or mulch of choice.

3) DUST THE SOIL — Numerous materials, when scattered in a thin unbroken ring around the plants’ stems, will inhibit slugs from reaching your plants. Your coffee grounds, for example, will serve as both a deterrent and a poison. The journal Nature recently reported that caffeine is toxic to slugs and some companies have begun marketing a caffeine-based slug spray.
Ash from your wood stove will also work well, provided that it stays dry. Slugs don’t like the feeling of the rough material, which will quickly dehydrate their worm-like bodies that are primarily made up of water.
Though you may have ash in great supply, you can’t use it indefinitely because it will eventually raise the pH of your soil too high. After a few applications of ash, you may want to switch to a product known as diatomaceous earth. Mined from the ocean floor, diatomaceous earth is the sharp, jagged skeletal remains of microscopic creatures. It lacerates soft-bodied slugs, causing them to shrivel up and die. It looks and feels like a white powder, but you’re advised to use a dust mask when applying diatomaceous earth; it can irritate eyes and lungs.

4) INSTALL PHYSICAL BARRIERS — Nature’s most fool-proof tool in the war against slugs is copper, which slugs find irritating. Many garden centers sell thin copper strips, which can wrap around the base of plants, or plant pots. We used two-inch wide strips in our trials and had excellent results.
Some gardeners will purchase fine copper wire and coil it loosely around plants. Keeping the coil loose will give the plants plenty of room to grow. Whether you use the strips or the coils, be sure no part of the plant hangs over the copper and touches the ground, otherwise the slugs will have a “bridge” to get to the plant.
We didn’t try this one in our garden, but heard from others that lava rock can be used as a slug barrier around plantings. The rock needs to remain on the soil surface and form a continuous wall, otherwise the slugs will find any opening to crawl through.
Crushed eggs shells may also be used in a ring around the plants — if you can find an ample supply of shells. The shells’ sharp edges will deter slugs from crawling. Slugs also won’t crawl over dry sand, but we found they will happily move over wet sand.

5) GROW BARRIER PLANTS — Mary Snider, a master gardener from Ogdensburg in northern New York, sent us this idea: “Garlic, ginger, chives, red lettuces — not green — and most of the mints generally won’t be touched by slugs. Grow these plants on the edges of your garden. Most of these plants, with the exception of red lettuce, generally won’t be eaten by deer or other critters, either.”

6) JUST KILL THEM — If you’ve had it, or you don’t want to mess around with barriers, mulches or soil dusts, you can go out in the evening and simply kill the slugs instantly. The salt in your table salt shaker will cause the slugs to quickly shed their outer shell and die of dehydration. A big question with this method concerns how much salt your soil can tolerate and most people we talked with don’t recommend using this method more than four or five times during the season.
A spray solution of household ammonia, mixed with 25 percent water, will also kill the slugs quickly. Experiment with this method in your own garden before going full bore. If the ammonia solution is too strong, it can damage the plants. And because the ammonia will instantly combine with the nitrogen in the atmosphere to create ammonium nitrate — a usable form of nitrogen fertilizer for the plants — it is possible to overfertilize and burn plants with too many applications of ammonia.
Picking slugs off the ground or plants by hand, of course, always works . . .

7) SHARE YOUR BEER— Often cited as a great way to attract and trap slugs, beer does work. Put a tin can filled with beer in the garden and bury it in the soil with only about a half-inch above the soil line. Slugs will crawl in and drown. The drawback, however, is that you’ll have to refill the beer every couple of days, and you’ll need to have a tin can of beer for about every three-square feet of garden space. Note: Keeping the lid above the soil line is important; if you place the lid flush with the soil line, you may trap beetles that are natural slug predators.
A far more potent trap operates on the same principle as beer. Since the slugs are drawn to the yeast in the beer, you’ll get even better results by creating a home yeast mixture. Pour two cups of warm water into a jar and add a packet of dry yeast. Add in about a teaspoon each of salt and sugar for good measure.
After mixing the solution, divide the contents equally into another jar and place both jars in the garden at an angle, so that the liquid is almost pouring out onto the soil. This potent mixture will draw slugs from several feet away and last a few days. When the jar is full of drowned slugs, you can add them to the compost pile.

8) SET OTHER TRAPS — Gardeners have no shortage of contraptions designed to lure slugs, which will look for any damp area to wait out a sunny day. You can 1) overturn a wet clay flower pot with just a small opening near the soil for the slugs to crawl through; 2) cut a grapefruit in half and turn it upside down; 3) place a wet board, log, newspaper or plastic bag near the garden. All of these will gather slugs for you; how you dispose of them —barehanded or gloved, with scissors or daggers, or by drowning in a bucket or flushing in a toilet — is up to you. Every slug you collect is one that won’t eat your plants and won’t lay eggs for future generations.

9) TRY SAFE COMMERICAL PRODUCTS — New products made from iron sulphate will lure and poison slugs and these reportedly work well. Escar-Go and Sluggo are common trade names of the same organic product that is safe for birds, pets and the environment.

About The Author

Paul Tukey

An international leader of the green movement, Mr. Tukey is a journalist, author, filmmaker, TV host, activist and award-winning public speaker, who is widely recognized as North America's leading advocate for landscape sustainability and toxic pesticide reduction strategies.

Number of Entries : 1024
  • http://www.herb-arium.com Beuna

    Great information! Diatomaceous earth works great unless it gets wet.

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  • jan mayberry

    What the heck are slugs doing to you guys? I have a beautiful, chemical free garden & lawn, with absolutely no damage, while I do have a huge and abundant population of leopard slugs everywhere else! They do eat out of my cat’s outside food bowel – could they prefer dry cat food? The only problem I’ve had with them is walking on them barefoot at night – YIKES!

    Give the slugs a break! (and some cat food!)
    Jan

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  • Lee

    For me, earwig beetles are much more of a nuisance than slugs… anything to deal with them?

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