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How to Get Rid of Slugs with Copper

Slugs in the garden can be a huge problem and apparently copper is a good slug repellent. If you encircle your plants with copper tape, it will keep the slugs out. It must work – since there are a number of copper tape products on the market designed to get rid of slugs. But does this really work?

How to get rid of slugs with copper

How to get rid of slugs with copper

Why Does Copper Work?

There are two reasons given for copper working as a slug repellent; toxicity and electric shock.

Copper is a known poison for many organisms and some copper chemicals are used to disinfect and kill organisms. It seems to make sense that copper tape or copper wire would have the same effect. If you think about this for a minute you will realize this can’t work. Most homes in North America use copper pipe to deliver water in our homes. If it were toxic – would we be using them?

Copper compounds may be toxic, but copper metal is not.

The green patina developed on copper metal over time is a copper carbonate salt and could be toxic.

The second claim is that the slime from slugs connects with the metallic copper and the slug gets a small electrical shock from it. This is unpleasant and slugs stay off the copper.

I have not been able to find any scientific reference showing that this is true. It is just repeated thousands of times. So let’s apply some logic. You can create a simple battery by inserting copper wire and a galvanized nail into a lemon. This will produce a small current that is measurable. You need 3 important components to make this work; two electrodes of different metals, and an electrolyte–the juice in the lemon. If you want to see a lemon battery in action have a look at this video.

In the case of the snail we have the copper, and the electrolyte in the form of slug slime.The second electrode is missing. Also missing is the connection between the two electrodes which allows the current to flow. I don’t believe that putting slime onto copper will produce an electric charge.

Does Copper Repel Slugs?

Let’s look at some video evidence.

Source: Does Copper Work on Slugs? See and Decide for Yourself! Just for fun!

 Copper pennies and wire do not seem to work. Most products on the market are a type of copper foil or copper tape so this might work better and in fact some people suggest that a wider strip is better than a narrow strip.

Source: Copper Tape vs Slugs

That seemed to work quite well. But what about this video?

Source: Garden Pest Update: Slug vs Copper

Maybe some slugs hate copper more than others.

And this one:


Source: Slugs vs Copper Tape

How to Get Rid of Slugs

Jeff Gillman, one of the Garden Professors, commented “When I’ve tested copper the slugs seemed to have a slight preference for not crossing it, but would if that was what they need to do to get where they were going. I’d call it a mild repellant” . I think this is a good summary. Slugs will not go out of their way to cross copper in tape form, but it is not a fool proof solution.

This myth is busted!

Other popular methods for getting rid of slugs include coffee grounds, and beer. For more information on these methods have a look at:

Getting Rid of Slugs With Coffee Grounds

Do Beer Traps Kill slugs

References:

1) Photo Source: Aspen Grove Gardens

Robert Pavlis
Editor of GardenMyths.com
I live in southern Ontario, Canada, zone 5 and have been gardening a long time. Besides writing and speaking about gardening, I own and operate a 6 acre private garden called Aspen Grove Gardens which now has over 3,000 perennials, grasses, shrubs and trees. Yes--I am a plantaholic!

I hope you find Garden Myths an educational site that helps you understand your garden better.

64 Responses to 'How to Get Rid of Slugs with Copper'

  1. TEMBEKA MQADI says:

    Copper definitely works according to the gardening experts.
    http://www.gardenersworld.com/how-to/maintain-the-garden/how-to-deter-slugs-with-copper-tape/

    • Your so-called experts is a what we call a click bait site. They write any type of garbage to get readers to their pages so you click on links and they get paid.

  2. Chica says:

    Thanks for saving me the $50 or so I was about to spend! There’s so much info like this on the internet, that’s repeated thousands of times as you say, so MUST be true…except it’s not…
    Very useful blog you’ve created!

  3. Bass says:

    Save money, I bought 3different types of sand. Didn’t work either. I’ve tried copper, I make jewelry and have lots of scrap in different gauges. None work. I have found DE works but if it gets wet ( watering plants) it doesn’t work so you must reapply! I will try slug bait but hopefully won’t attract snakes!

  4. Jannette says:

    My friend suggested garlic water sprayed on the plants and left to dry. Apparently they don’t like the taste. Reapply every 2 weeks. Recipe below. Does this work?

    https://www.bowdenhostas.com/pages/Garlic-Wash-Recipe.html

  5. Charle101 says:

    I’ve tested solid copper rings which I made from some spare copper roofing strip. Did it work? Yes and No; the difference is oxidation.

    I put a clean shiny copper ring on the ground and filled it with a dozen or more slugs and snails. It worked; try as they might none of them could escape. Even when climbing over each other to form a mound the height of the ring. The snails on top would stretch out to touch the edge of ring and withdraw immediately. It looked liked they were reacting so some unpleasant stimulus. When I used a dulled oxidized ring they all climbed out is short order.

    Because I have the rings already I use them and they work well but only for a couple of days, until they oxidise. However that is long enough for my beans etc to get going up the poles and out grow the slugs. When I want to use them again I remove the oxide by dropping the rings in a bucket of water with a tea spoon of citric acid.

    Your ‘deductions’ about ‘electric current’ appear somewhat limited. Having worked in roofing for a few years I know not to combine certain metals together because they can corrode as a result of contact in the presence of water unless they are electrically compatible.

    I am not a chemist but guess it is due to some kind of ion exchange or electron donation. My guess is that something similar is taking place between the bright copper and the molluscs. Roofing metals are chosen for the job because their oxides adhere to their surface and are chemically inert under normal atmospheric condition. Knowledge of this fact is what lead me to triy the experiment in the first place.

    I wouldn’t waste my money on copper tap because my experiment shows it could only have a very temporary effect if any. I’m not sure I would buy the rings ether if hadn’t had the spare metal. Copper scrip is expensive, I haven’t purchased any more even though I know it works under the right conditions. Perhaps I’m waiting to see how long my current 24 rings last given the need for repeated soaks in citric acid.

    • Certain metals, when they touch do undergo a chemical reaction. But I don’t think they produce a conducting current.

      • Charle101 says:

        You may be correct. As I said I am not a chemist. Although I’m not sure that ‘Conducting current’ is the same as ‘exchanging an electrical charge’. But who really cares. The issue is whether or not it works and if so, under what conditions.

        My criticism of your comments on ‘Electrical current’ as it related to the use of copper is that it represented a deductive approach not an empirical one. Things often fail or succeed for reasons other than we anticipate. There is no substitute for testing.

        The problem, as your blog highlights, is that different tests gave different results. In one video the copper was wet and in another it was dry as you and others pointed out. But in addition the wet copper was shiny and the dry copper was dull; surface oxidation. Some of the test used copper foil, I used much thicker copper strip (0.6mm). I don’t know all the variables at work here. I was only pointed out my experience in order to help others make a choice. As I’m sure you were.

        I’ve worked out that fashioning the copper rings myself from a 10m roll of 50mm x 0.6mm thick copper strip (£51) would cost out at about £1.50 each (33 rings). I already have the basic tools which would otherwise cost around £40.

        I’ve only used my rings about 6 times (twice per growing season). So far they show no real sign of deterioration so I’m definitely thinking about buying a 1/2 roll of copper just to make rings out of. I’m still a little concerned they might get stolen from the allotment. If I get beyond 10 uses I will probably bite the bullet.

  6. Patrick says:

    I have successfully kept slugs out of my planter by setting the planter inside a tray of salt. A situational solution, but it’s worked for me.

  7. Diy Dear says:

    Slugs are a huge problem in my garden. I was able to write a whole blog post about the damage they’ve done to my seedlings (). I don’t know what method I should try next. What do you suggest?

  8. Marian says:

    Yeh well! What about a mearing of petroleum jelly all around he neck of hosta pots. This seems to work for me, but means you get messy when trying to move the pots around. What is the evidence?
    I think some manage to helcopted in,anyway!
    I am southern UK resident.

  9. laila says:

    so what DOES work to deter slugs please? 🙂

    • If you search the blog for slugs you will find a number of posts about this topic.

      Beer works a bit, but most slugs just drink the beer and leave. Commercial bait works. Home remedies don’t.

    • Marni Suliin says:

      1/2 -1/2 solution of vinegar and water. Put in spray bottle and hunt them down! If you have kids give them a bounty. Go out early in am or very close to dusk. It doesn’t hurt plants or soil,bout it melts slugs!

  10. Erin says:

    Hi there. People and inverts are different 😉 the copper pipe that gives us safe tap water will wipe out the invertebrates in my aquarium. Heavy metals are toxic for all of us in high enough doses, we have amuch higher tolerance than invertebrates. There are times I’ve had to use reverse osmosis water for my aquariums because of this. Copper treatments are used for fish because the copper kills invert parasites and doesn’t harm fish in lower doses, but it can wipe out reef tanks or desirable fresh water inverts, like snails.
    Clearly you like Teh Science so here’s a data base of studies for inverts. http://www.pesticideinfo.org/List_AquireAcuteSum.jsp?Rec_Id
    Don’t want to write a novel in your comment section, you get the idea. And it also makes sense, sort of, why someone thought copper tape would work and also why in reality why it wouldn’t. 🙂

  11. craftyjay says:

    Have been trying out lots of ways of stopping slugs and snails and came to the same conclusion as yourself – copper tape on its own does not stop them. Tried coffee grounds, egg shells and other rough surfaces (have even tried inverted wire brushes – again does not work). The only thing (apart from pellets) that does work is two strips of copper with a voltage between them. Have developed a unit that can use existing copper tape and allows you to check if it is working with a battery life of 2 to 3 years. To date it has had 100% success on large pots and I am now going to try it on a raised vegetable patch.

    • Kate Russell says:

      craftyjay – I would LOVE to see an Instructable on your idea!

      • Colin says:

        stick two copper tapes to the pot, in 2 rings about 1/2″ (1cm) apart. Get a 9V PP3 battery, and clip, the one with two wires and the clip (maplin sell them) and stand the battery behind the pot, with the wires connected, 1 to each ring. This will use no current so the battery will last 3-4 years, but will be enough voltage to stop slugs.

      • Koen says:

        Here’s a video on this idea including test with slug. Works!
        https://m.youtube.com/watch?v=ZoBeKS64_xc

  12. biki says:

    Hi Robert! I just heard your interview on RootSimple blog and thought it was really informative and eye opening. I have a question about copper and salt but not in relation to slugs. My studio in my backyard uses ferric chloride liquid to etch copper plates (i’m a printmaker). I have heard that both salt and copper are very toxic to soil biology, so I would have never thought about disposing of it in the ground and normally keep it in a jug and wait until i can bring it to a proper disposal place. The amount of ferric chloride with dissolved copper bits in it amounts to maybe a half a cup a month (if that) that I usually dilute 4x and add baking soda to to neutralize it. Is it safe to drain into some kind of french drain into the ground? Is this a horrible idea? Thanks so much for your answers and thanks for your helpful blog!!

    • This is not really my area of expertise, but adding copper and sodium to soil is not a good idea. It would be better to collect it and dispose it with a recycling facility.

  13. Malcolm says:

    Regardless of the use of copper strips or electricity, some types of slugs have been know to drop down from overhanging trees or even lower themselves down a slime trail.
    I suggest that people who say one or another methods works, should actually go out into the garden for several nights (wet and dry) to see how many slugs there are and how many get past the trap before claiming it works based on one test or saying that it ‘seems’ to have a effect.

  14. D.M Rooms says:

    I’m precarious about buying copper tape as it’s quite expensive and if it doesn’t work , I been using slug pellets and that I think is the best repellent , a line of salt around the base of pots can work also , and is a lot cheaper option. Good luck with it . 😀

  15. Judy says:

    Hi Robert, thanks for the post. You’ve saved me some money! Do you have any advice on what does work? Every year our hostas are decimated 🙁

    • The only thing I know that works is slug bait. The new versions are quite safe.

      Encourage snakes and toads in the garden. make nice shelters for the latter.

      • Judy says:

        Thanks for the feedback. I’ve never seen a snake around here in eight years (maybe they’re hiding), but toads yes. I’ll see what I can do to make them feel at home 🙂 Will slug bait harm the toads?

        • Probably. Amphibians are affected by most chemicals more than other life forms. But I don’t know if a toad would go and eat the bait. It will also depend on the type of bait. You can cover the bait and leave a small opening for the slug.

          • Hi find copper tape works where the plant is not close to a wall or other plants where slugs and snails can climb/drop/absail across etc. i have a wildlife garden with frogs,toads,sloworms and birds,so don’t use chemicals.In the UK we have pellets made from waste sheep fleece, i surruound young and slug prone plants with this and it forms a mat when wet which slugs and snails don’t like to cross, by the end of the season it breaks down into the soil but by then the plants have toughened up.

      • Ironically, so does putting beer into an aluminum pan to deter them away from plants… They love beer and if they land in it they drown. I tried this yesterday and attracted 7 slugs away from my plants.

        • Philip Croft says:

          “putting beer into an aluminum pan ” ” if they land in it they drown. I tried this yesterday ” ….and at a guess, I’d say you probably didn’t drown…It would however be a great way to go 🙂

    • janet says:

      I spread oatmeal and see no more damage after that (they eat it n blow up) you have to keep spreading it every few weeks or so but it works!

  16. Trixie Spark says:

    The copper works in the garden, so I suspect there is a reaction between the copper and the soil that can cause the copper to charge up to shock the slug. I would like to see a test like that with the wire in the soil around the garden bed.

  17. Dave says:

    Thank you for this info. I have recently tried putting segments of copper wire scattered round some plants. As yet it is too early to tell if it will have any affect. With reference to the theory of the electric currant being created you suggested that two different metals need to be present and this is correct. May I suggest that the natural iron in the soil would provide the anode for the production of a small electric current to occur. If my experiment proves non productive then I think that I might scatter some old nails around as well as the copper.

  18. diverte says:

    thanks very useful saxed me some pennies

  19. i still would like to know if sand around your garden will keep the slugs out also .
    will oyster shells stop slugs.
    addison

    • Someone else posted about oyster shells. A quick search found only people who have tested it and say it does not work. Don’t know about sand – but there are so many kinds of sand to test. But I doubt sand works. Slugs are designed to crawl over things in nature – where there is lots of sand.

      • Debbi says:

        I used crushed oyster shell around my plants and it works as long as I cover the full area, out to the tips of the branch line, and refresh it if plant debris from overhanging plants fall onto the shells. Debris acts as a bridge that the slugs use to cross to the plant. I also use Sluggo (iron pellets) with less success. Pacific NW is slug heaven.

  20. Carrie says:

    The copper tape works when it’s wet which the second video shows. The problem is keeping it wet.

    • Thanks for the comment. I had noticed the copper tape was wet. So I guess if you are willing to spray it every hour it works!

      • Kate Russell says:

        I don’t think wet is enough. I invested in some adhesive copper strips (before reading this post) and conducted my own test this morning – with dew all over the copper strip. Slugs were harvested and put to the wire, so to speak. They crossed it without batting a tentacle. Back to pellets for me… (Love the blog!)

  21. You could try using 2 copper tapes with a 1.5V battery connected between them. (I’ve not tried it myself) I’ve long given up and gone back to slug pellets

  22. Nathan says:

    My only slug repellant is the colony of leopard slugs that lives on the property. They’ve never touched anything in my garden aside from smaller slugs and dead plants.

  23. Paul Staples says:

    So, perhaps what is needed is a bi-metallic barrier, say a strip of copper tape, a small gap, then a strip of aluminium foil. Slug may cross one but will get a shock when he straddles both, and hopefully turn back.

  24. Lana says:

    Oh no thank you for the video was most helpful ! I think will try my eggs shells and sand idea ! Save a bit of money !

    • Robert Pavlis says:

      Your welcome. Egg shells don’t work well either. Apparently diatomaceous earth works–but you need to use the one made for gardening, not swimming pools.

  25. cine says:

    What if you twisted a copper and a galvanized wire together? Those two metals plus the slime would create a current?

    • Robert Pavlis says:

      I believe the two wires would have to be separated and the slime make the connection for this to work, but I am not sure. In any event I have never seen this as a solution to the slug problem.

  26. jacecil says:

    I was suckered in to buying copper tape. DID. NOT. WORK. http://imgur.com/Y6P8xER

    • Robert Pavlis says:

      That is one of the reasons I write this blog. There is too much useless stuff on the market to buy. Only the truth will set us free.

  27. Great to see… to add to the video list, I liked this one on the topic: http://www.youtube.com/watch?v=ZFn9TT_rlXU

    Same basic conclusion.