Copper strips are available in some garden centers and by mail order. Slugs will not cross copper. This is one method that works even after it has rained. As a last resort, there are poisonous baits designed for use against slugs and snails. They contain the chemical metaldehyde.
Poison baits are usually available as pellets, powder or gel.
All need to be reapplied after several rains. The drawback with poison baits is that they might also poison some of the natural predators of slugs such as toads, snakes and birds. Pets and small children may be attracted to the pellets, too. Use them carefully and follow all directions and cautions. Inc. All rights reserved.