Controlling Slugs in your Garden

Garden slug

Most people are completely repulsed by slugs, and who can blame them? They are gooey-sticky-slimy, leave those nasty snot-trails everywhere, and eat up your plants!  Fortunately, there are many options available to deal with slugs (and their backpacking cousins: slugs). Even better, all these options are organic, so you can use them safely throughout your landscape—even in the vegetable garden.

The slug control that gets asked about most in New Garden’s garden centers are beer traps. They are cheap and easy to use. To make a beer trap, use a fairly deep, narrow container like a yogurt or sour cream container. Bury the container in the ground so the lip is level with the soil, in the area you have problems with slugs.  To make it easier to empty, bury two containers nested together so you can lift the inside one out.  Fill with beer-the more yeasty the better since the yeast is what attracts them. (Feel free to personally sample possible beers until you are satisfied you’ve chosen a good one. Teetotalers can fill traps with a mix of water, sugar and yeast). Contrary to common opinion, the slugs don’t get drunk and die happy in beer traps. No, you’ll be tempting them with delicious yeast to go swimming in beer-and slugs can’t swim. They work pretty well, but you’ll have to empty the trap of drowned slugs regularly and keep the beer topped off.

Another simple slug solution is diatomaceous earth (DE).  DE is the skeletal remains of tiny, seagoing creatures (diatoms) ground to a powder. On a microscopic level, the powder is made up of razor-sharp shards that cut open slugs and insect pests like tiny knives, causing them to lose body fluids, dry out and die. You should avoid inhaling DE, but it is considered non-toxic, even to the point of being offered in food-grade formulations. (Don’t use DE for pool filers as slug or insect control-that is not safe to put in your garden.) Sprinkle the DE around your problem areas and it will kill slugs and other insect pests. The downside of DE is that it doesn’t work well after it gets wet, making it problematic during rainy weather.The plus side is it’s a terrible way to go.

Using copper to deter slugs is expensive, but the strips can be reused for several years. Copper is sometimes saved for particularly valuable plants. Strips of copper at least 2-3” wide are inserted edge-first into the ground, forming an unbroken wall around the plant you wish to protect. Merely laying them flat on the surface may allow slugs to crawl under them. (Make sure there are no slugs inside the barrier to begin with-you may need to use hand picking or bait to clear the inside of the area.) It is thought that the moist body of the slug receives an electric shock-like jolt is they try to crawl across copper.

Iron Phosphate Slug Baits (brand names include Sluggo and Escar-Go) are extremely effective, easy to use, and safe around children and pets. Simply sprinkle around the area to be treated-they are even safe to use around your vegetables. Reapply every few days after heavy rains, or less frequently in dry periods. Bonus-slugs stop feeding (and destroying your plants) almost immediately after ingesting the bait, then politely crawl away to die underground. Bonus bonus-the iron phosphate acts as a plant fertilizer as the bait breaks down.

Slug eating a leaf

Slug eating a leaf

If you like to get hands-on in the garden, hand picking or using traps in the garden can provide hours of fun. To hand pick, look for slugs early in the morning or after sundown in moist areas, on the underside of leaves, under rocks etc. (I hope we don’t have to remind you to wear rubber gloves to do this). You can make them easier to pick by leaving traps that slugs will use as hiding places as morning approaches: pieces of board, flat rocks, melon or orange rind halves, or damp rags work great. Simply lift up your traps after a day or so and collect the slugs. How you choose to dispose of them is up to you, but here are some ideas-smash them, salt them, drown them in soapy water, feed them to your pet bird, have slug gladiator fights.

Speaking of feeding, you can invite some help to your garden by encouraging slug predators to hang out. Toads eat slugs and other garden pests and won’t harm plants at all.  Plants with large, low leaves like hostas, brunnera and ligularia create ideal hiding places for toads, as does putting toad houses in moist, shaded areas. Making your garden inviting to birds will also reduce slug populations.

You’ll get the best results by using a few of these methods together, and adjusting for conditions. You’ll need to be more aggressive during periods of wet weather and while plants are young and vulnerable. During warmer months, a few sprinkles of bait and a friendly toad will probably keep your slugs in check.