Copper barrier. When a slug crosses a copper barrier, its moist, mucusy body reacts with the copper and it receives an electric shock. Copper barriers can be pushed into the soil to make a vertical fence around a plant or bed, or laid flat. Either way, use 2- to 3-inch strips. Yes, this product can be costly, so save it for your most prized plants or where the slugs are congregating. Rolls of copper barrier are sold at Planet Natural.
Sluggo. This nontoxic slug bait (iron phosphate is the active ingredient) is safer than metaldehyde baits, which can harm pets and wildlife. Sprinkle Sluggo granules around your plants and beds in the evening. Ingesting Sluggo causes slugs to stop feeding and to retreat underground, where they die within three to six days. Galloway tested Sluggo and found that it works well as long as you consistently reapply (about once a week). She uses it in conjunction with beer traps for better control. In dryer regions, you may need to reapply only every two weeks. Sluggo is sold at Gardener's Supply or Harvest Safe.
Red clover. Slugs love this easy-to-grow legume, concludes a recent study from Harper Adams University College in Shropshire, England. Researchers found that when this alternative source of food was planted next to beds, slugs were lured toward the sacrificial clover and away from more valuable plants. Resilient (and beautiful), red clover grows in a wide variety of soils. While the clover lasts, this method substantially reduces slug damage. After it fades, cut it down and incorporate it into the soil as nitrogen-rich organic matter.
Hand-picking. Not every gardener enjoys this (though we know some of you find it to be wicked fun), but the results are guaranteed. "I have yet to find a slug control that is more surefire and easy than a daily hand-picking patrol when pressure is high," Debbie Leung claims. In the early morning and early evening during slug season, pluck as many slugs as you can find (Debbie sometimes collects 200 in a day). Cut them in half or drop them in soapy water to kill them. For easier picking, encourage slugs to congregate by laying wooden boards or roofing shingles along garden paths for slugs to hide under. So which method works best? None of them control slugs 100 percent of the time, but our experience finds that any of the methods combined with hand-picking keeps slugs and their damage to a minimum.