If you are a gardener who grows in raised wooden beds, this tip is for you.
We know that slugs are deterred by coarse, sharp surfaces, which irritate their undersides as they move along the ground. As a result, we've seen lots of tips for how to use this to our advantage, and keep those pests away from our lettuce or other garden plants. Tips suggest scattering broken eggshells, sharp gravel, or other coarse items around garden plants to keep slugs away. If you grow in raised wooden beds, there is an even easier way.
Go to your hardware store or home center and look for waterproof sandpaper in a coarse grit, such as 80 grit. Sandpaper recommended for drywall sanding is usually a good option - but make sure it is labelled "waterproof." You'll need enough to cover the top of your raised bed frame, so figure out how much you need based on the perimeter of your bed.
Once you have your waterproof sandpaper, it's time to install it on your beds. Simply cut the sandpaper to size so that it fits the top of your raised bed. You can either staple it flat on the top, or bend the edges of the sandpaper down the sides of the bed a bit and staple that way. You just want to make sure that you pull the sandpaper tight to the wood before stapling; you don't want any gaps for the slugs to go under and get into your beds.
This installation makes a barrier of coarse sandpaper all the way around your bed, keeping slugs out for good. Keep an eye out for any slugs that are already in the bed, and remove any that you see. Once resident slugs are evicted, you will have a slug-free garden bed.
In most climates, the sandpaper will last at least a couple of years before it will need to be replaced.
There you have it: an easy tip to keep your raised bed gardens slug-free!