In this article I’ll present a foolproof method to keep slugs out of your raised bed. Bill of materials:
– 9V battery with connector, some claim that 4 AA batteries (6V) in a case should do as well
– 0.5mm (0.02”) electrical wire, non-isolated
– small plastic box with cover
There are lots of myths as to what is supposed to keep keep slugs out of your raised bed or out of your garden in general. Folks recommend egg shells, diatomaceous earth, ground coffee, aluminum foil, copper foil, etc. etc. Unfortunately those methods are just that – myths. Youtuber Bob Kelland proved them all wrong.
Unless you want to check your garden beds (at least) twice a day and pick’n kill the slugs manually I suggest you install a simple electrical slug fence for your raised bed.
Keep slugs out of your raised bed – the idea
Create an open circuit of two wire rings around the raised bed. The circuit is closed once a slug attempts to cross both. Result: a small current of 9V flows through the slug. It won’t kill it but it will make it turn around.
The beauty of this method is that it electricity only flows when a slug crosses the wires. Thus, a single 9V battery will easily last an entire season.
Install the wire
I used 0.5mm galvanized wire because it promises to be much more resistant to corrosion. Rusty wires would be much less effective.
Wrap and staple the wire twice around the raised bed. I separated the two wires by about 2cm. Twist them together where the ends of each wire ring meet. You need about 15-20cm extra here.
Attach a battery box
The battery box can be screwed / nailed / glued / etc. to the raised bed around where the wires meet. Drill two holes and feed the wires into the box.
I opted to drill one hole at the top and one on the side to reduce (ok, eliminate) the chance of them accidentally touching. It’s the slug that should close the circuit not the wires.
The final touch is to seal the holes with hot glue. If you can’t / don’t want to use hot glue you could feed the wires into the box from the bottom. This reduces the chance of water inside the box.
Installing the battery
The final step is again a trivial one: attach the two wires to the battery connector. This can be crimped or soldered or improvised.
Now add the battery and start testing – with a voltmeter or a slug.