Papou, something about when the slug tries to crawl over it they get a shock and it deters them from crawling over it. However, if they are already in the circle, it keeps them in for the very same reason. :) I think it would be cost prohibitive to circle all your hostas in copper...

Diann

I have also heard of this method. I was thinking of trying it myself but want to know if you can make your own rings out of copper wire, what gauge wire, or if you can buy the rings at a reasonable price and where. I only have about 60 hosta and not a large problem with slugs at this point. I thought if I used the ammonia treatment also in the spring when the eyes are just emerging and shortly afterward - in conjunction with the rings - then maybe the slugs would be under control. Any ideas? Thanks Sue

I have also read you can use pennies scattered throughout the beds for the same reason. I've never tried it, so I don't know if it works.

It does work but only for a relatively short time until the copper starts to oxidize. The conduction of the electricity goes down with the oxidation. Leaves and other debris also will fall over the ring allowing a convenient access also.
Bob

I thought one would use the standard water copper pipe in houses...1/2 in diameter....maybe I'm wrong.
Has anybody used copper pipe with success?
Papou

I went to the craft store and bought copper sheets in the area for doll houses. It comes in a tube and is used for the roofs I think. Anyway, it works. The edges can be very sharp. I've cut myself on them and so have the dogs. I finally cut the strips double the width and folded it in half before I put it around the hosta.

I've heard of this one over the years, but it doesn't make good financial sense to me. I'm assuming the copper would have to touch the ground, otherwise a slug could crawl under it. So the ground would have to be very level all the way around. Multiply that by several hundred hosta, and you've got a heck of a bunch of work. I say, GO SLUG BAIT!

Lynn, I guess you're right...the good ole Sluggo and ammonia solution...

I read this claim sometime ago and this spring I decided to test the truth of the matter. I bought a small copper sheet and cut it into a thin strip. Then I bent the strip to form 3 sides of a square. I collected 2 nice huge slugs and lined them to face the sides with copper wall. And would you like to know how they behaved. One came towards the wall, and being obstructed, decided to squeeze under it and came out unpertubed. The other decided to scale the wall and showed hardly any uneasiness.
It is true that slugs hate to scale sharp edges but would still cross instead of going around the barrier. I won't use copper strips as they tax your pockets, rather I would spread a layer of crushed granite pebbles round the hosta. I wonder if the idea works.
After trying the copper, my friend, 80, who is a horticulturist suggested that I use a low electric charge on the strip. I thought the project is getting complicated and since slug bait is so effective, why bother to go any further with this claim. I always prefer to take the line of least resistance and that ended my quest. LOL