copper tape has some effect.

After numerous experiments and thorough investigations, it has become evident that copper tape, copper mesh, and copper pipe are not entirely reliable as protection against these garden invaders. However, they may help reduce slug and snail damage overall, as they seem to have some repellent effect. Copper can be used as a barrier for potted plants and those planted directly in the ground, but I believe there are better barrier options available—and here’s why.

Below is an overview of our experiment to test whether copper (in the form of tape, mesh, and pipe) could prevent slugs and snails from eating plants. The experiment revealed that copper did not stop them, as slugs and snails were able to cross the barriers, as shown on the right. However, this doesn’t mean copper has no repellent effect; rather, it demonstrates that slugs and snails are capable of overcoming it. To investigate this further, we carried out another experiment.

In our second experiment, we aimed to determine whether copper has any repellent effect on slugs and snails. To test this, we designed an experiment to see if slugs and snails would prefer to move over copper or a different metal, which acted as our control. As shown below, we placed numerous slugs on a slugstand filled with salty water, forcing them to exit only via the pipe pathways. We then counted how many slugs left via the chrome-plated pipe and how many left via the copper pipe. If copper had no repellent effect, we would expect an equal ratio of slugs leaving through each pathway—for example, 10 via the chrome pipe and 10 via the copper pipe.

In our experiment, 20 slugs left the slug stand, with many attempting to cross the moat, as shown in the picture below. Ultimately, 19 slugs exited via the chrome pathway, while only 1 opted for the copper pipe exit. These results lead us to conclude that copper does indeed act as a repellent for slugs and snails.

However, this raises the question: should you buy or use it? Our recommendation is that copper would very rarley be our first choice as a barrier. That said, it still has a place in a gardener’s toolkit.

The benefits of copper are that it’s environmentally friendly—it’s not plastic and poses no harm to wildlife—and it does demonstrate a repellent effect on slugs and snails. On the downside, there are more effective and impassable barriers available, whether you’re protecting plants in containers or those planted directly in the ground.

For a detailed look at this experiment and our other barrier tests, check out our YouTube channel via the link in the footer below.