Controlling Slugs Organically in Gardens

Know your enemy - the spotted garden slug.
Know your enemy - the spotted garden slug. | Source

Organic Slug Control Solutions for the Home Garden

There are many Organic Slug Control solutions for the home garden over and above the traditional advice of putting out a saucer of beer (which actually works; slug die happy, but they do die.) Whether you choose to make a homemade Organic Slug Control or purchase some of the many organic gardening slug control products available at your local home and garden center, the following tips will help you control slugs in the garden and prevent damage to plants, especially hosta, a favorite plant for slugs to eat.

What Are Slugs?

The common garden slug is actually a mollusk, related to snails and other land mollusks. Think of them as snails without shells. They can be brown, gray, striped or spotted and have two eye stalks. They like moist habitats with lush plant materials and are found in shady, damp areas of the garden. They eat plant material, either leaves or fruits such as tomatoes. You can tell you have problems with garden slugs by observing the following signs:

  • Slimy silvery trails - this is actually a mucous secretion the slug produces under its mouth to help it glide along to its next plant victim.
  • Unevenly munched plants - slugs chew uneven holes inside leaves or along plant edges.
  • Actually seeing a slug - the spotted brown garden slug is unmistakeable.

Slugs love dark, moist places. That's why if you have a slug problem in the garden, it's important to make your garden unattractive to slugs. If you have piles of leaves, plant material, or old boards in the garden, pick them up and discard them. These are places where slugs love to hide and lay their eggs.

Beer for your slugs! It's an organic slug killer.
Beer for your slugs! It's an organic slug killer. | Source

Organic Slug Control Methods

Gardeners concerned about the environmental impact of using chemicals in the garden should seek and use Organic Slug Control methods. Although they can be a little more labor intensive than chemical slug control methods, they do work.

How to Make a Beer Trap for Slugs

For some reason, slugs love beer and anything fermented. Beer traps lure slugs to their death. They enter the trap to sip the beer, then drown in it.

Two methods to make beer traps for slugs include:

  1. Leaving open bottles of beer on their side in the garden hidden in areas that slugs frequent. Leave about an inch of beer in the bottom of the bottle. Slugs crawl into the neck of the bottle, enter to drink the beer, and drown.
  2. Place an old pie plate or tin in the ground, burying it so that the lip is at ground level. Fill the bottom of the pie plate with beer. Slugs crawl in and drown.

Whenever you're using beer to trap slugs, use a bitter beer and do not use lager. Yes, slugs can tell the difference. I have no idea how, but the book "Tips from the Old Gardeners" confirms that garden slugs are snobs about their brew. They won't fall for lager traps, only true beer traps.

Gravel and Oak Leaves

Slugs dislike passing over both gravel and oak leaves. Gravel has sharp edges, which can cut their soft bodies. Use gravel for pathways, or as decoration and mulch around ornamental landscape plants.

Oak leaves produce tannins, a chemical that slugs also do not like. Shredded oak leaves placed around your garden plants may deter slugs while also providing organic mulch that eventually adds nutrients to the soil. That's a winner for any garden, but especially for organic gardens!

Diotomaceous Earth Natural Slug Repellent

Diotomaceous earth is a natural slug repellent made from a silicon-based fossilized rock. Diotoms were a type of hard-shelled algae that were trapped and fossilizing inside rocks as the seas receded in ancient times. Today, they're mined and crushed into a natural powder sold as a natural, organic insect repellent for soft-bodied insects such as slugs. The tiny hard shells of the diotoms are crushed into sharp, jagged edges that cut into the slug's soft belly and kill it. Diotomaceous earth doesn't harm people or the environment. The only drawback is that it must be applied frequently around plants that slugs like. Rain washes it away, and dampness makes it less effective. Follow package directions when using it. You can find it at local garden centers.

Copper for Slugs and Copper Tape

A new organic gardening product sold as a slug repellent is copper tape for slugs. It comes in a roll or a package of thin copper with an adhesive back, so it's really best to use it on planters, window boxes, and raised bed gardens - places where you can completely encircle the garden area with the tape and it has something to adhere to. Copper is interesting because it works by chemically interacting with the mucous slugs secrete; the chemical interaction zings them like an electric shock, and they go away.

Another use of copper for slugs is to mix a copper powder (available in garden centers and home improvement stores in the nursery and garden section) with water and spraying it on plants. This acts as a slug repellent. Follow package directions carefully.

Protect Hosta Plants from Slugs

Hosta plants deserve special mention because they are a favorite target of garden slug attacks. Since hosta are primarily grown for their beautifully colored leaves, having slugs chew away the leaves and leave ragged, unsightly foliage is frustrating for gardeners. Hosta also prefer a moist, shady environment, which is the same habitat garden slugs love too. But there's a way to foil those nasty slugs, albeit on a small scale.

If you have only a few hosta, here is a natural, organic gardening solution to keep slugs away from the plants. Place your hostas in large pots. Dig a hole in the garden where you want the pot, but do not place the plant directly in the ground. Sink the pot into the ground and leave about 1/4 to 1/2 inch of the rim sticking up over the soil. Push the soil back around the pot, allowing the rim to stick up from the earth.

Now take a jar of petroleum jelly such as Vaseline or a generic brand of petroleum jelly. Wipe a thick layer around the rim of the pot. Now take gravel cat litter, gravel or finely crushed rocks and smooth that over the petroleum jelly.

Any slug trying to crawl up the side of the pot will find overwhelming defenses. The gravel, cat litter or grit will hurt. The petroleum jelly will make it slow going. Hopefully he'll give up and slither on over to your neighbor's garden, leaving your own hosta intact.

Manual Slug Removal: Ugly but Effective

Lastly, there's always manual slug removal, which is a nice way of saying find them and kill them one by one. Some organic gardeners leave what they call slug boards out near the garden. These are old pieces of scrap lumber. Slugs crawl underneath for the dark, moist area. When you pick up the board, you use a brick, trowel or salt poured onto the board to kill the slugs. NEVER use salt directly in your garden beds, as it poisons the soil and makes it impossible to grow plants.

One last organic gardening tip. Clean up your garden each fall. Rake up leaves, trim perennial plants, and use clean, fresh mulch. This reduces the places where slugs lay their eggs in the fall. Slugs lay eggs in the fall, which hatch into the next crop of the slimy monsters in the spring. By reducing their habitat, you'll make it harder for them to colonize your yard and ruin your plants.

© 2011 Jeanne Grunert

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Comments 5 comments

itsmonkeyboy profile image

itsmonkeyboy 5 years ago from London, UK

Great hub. Slugs destroyed our cabbages this year, I caught a few but was unable to stop them. Some great ideas there though, especially the beer one, I hadn't heard that before. Plus, it gives me an excuse to stock up on a little beer. Thank you!

Teregirl profile image

Teregirl 5 years ago from Pacific Northwest USA

Good article.

tillsontitan profile image

tillsontitan 5 years ago from New York

Interesting hub. I had heard about beer for luring slugs but had no idea it really worked, and its great to hear about Diotomaceous Earth - I use it in my pool filter but will certainly try it around my many hostas. Thanks Jeanne. Voted up and useful.

prasetio30 profile image

prasetio30 5 years ago from malang-indonesia

Very informative. My father love gardening. I'll show this information to him. I learn much from you. Thank you very much. Vote up!

Jessica 5 years ago

Another neat option are Slug Shields. They are one of the only solutions that I have found that last all season. They are also non-toxic.

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