Preventing Slug Damage? Copper Gardening Tools

Maddy Harland
Thursday, 11th December 2014

Maddy Harland puts a copper trowel to the test: can copper tools live up to the claims that they prevent slug damage on newly planted veggies?

I have long had an interest in copper tools, as I have done successful experi­ments with copper in the garden. Firstly, with some (expensive) bought copper rings to protect seedlings. Then, I made my own rings from old copper sheets. I am told you can also cut and flatten copper piping to make rings or even cut up a redundant hot water cylinder, but I digress.

I visited Charles Dowding, the no-dig market gardener and author, and learnt that he uses and recommends copper tools. Charles is both an excellent organic gardener and a pragmatist and so I tend to think that if he recommends something it is worth testing myself. He said, “There is certainly an element of mystery as to the benefits they bring, and the joy of using them adds to any other good effects. The enduring sharpness of all edges is also a great benefit.”

Tim’s birthday came around and he asked for a Mira Trowel, a great reason to purchase and test out the tool. I should explain that these tools are not made of pure copper, which would be too soft, they use an alloy containing 90% copper and 10% tin. So really they are bronze. This is not as hard as steel, but it is sharper (and keeps a good edge) and smoother, so there is less resistance from the soil.

A few days later a modest package arrived. Inside was a slim yet extraordinary trowel. It was a gleaming work of art, impressed with an ammonite symbol. I gave it to Tim and a few days later we put it to the test by weeding two no-dig beds which yielded a crop of garlic and broad beans earlier in the year, but had become a little weed-congested whilst resting.

The slimness and sharpness of the trowel means it is easy to bury deep in the bed to get under thistles, dandelions and other weeds. It doesn’t retain soil on the blade either. Appar­ently, this even works in clayey soil.

My next task was to plant some plugs of Japanese onion and red cabbage. Again, in my raised bed this took moments. To date, slugs have not eaten the unprotected seedlings although there was a little damage on the first night. They are growing well.

Why does it work? The theory is that steel tools contain iron which when used in the soil creates its own magnetic field. The slugs and snails are attracted to this field and enter it to investigate. Copper is highly conductive but has no magnetic field. When you disturb the ground with a copper tool you do not leave a magnetic signature and therefore slugs and snails are not attracted to the area you have cultivated.

Further investigations took me to Chalice Well Gardens where I spoke to the head gardener, Ark Redwood. He told me he has had great success with the tools and swears by them. So there you have it. These are tools that are beautiful and hard-wearing. They have a 25-year guarantee and my cabbage and onion seedlings, vulnerable without protective copper rings or a ring of crushed eggshells, have survived and are growing well. So dubious though I was, this is a recommend, and they make beautiful presents as well.

The Mira Trowel is available from our Green Shopping site along with a range of other copper tools, including forks and hoes. You can find the selection HERE.


Further resources

DIY copper slug rings for slug defence

20 ways to control slugs