A new product called SlugDefence , developed in Washington State, does an excellent job of keeping slugs out of areas where the fence is installed. Still, probably the most popular method of controlling slugs today is by using commercial slug bait products. Available in meal, pellets, powder, liquid, granules, and gels, their effectiveness depends primarily on the frequency of application and the way in which they are applied. It is important that all types of slug baits be applied only as directed on the label. Special attention should be given to any cautions on the label, especially where they pertain to children and pets.
Weather is also a factor in the effectiveness of baits.
If the bait can be covered and protected from sprinklers or rainwater, it will last much longer. You can cover the bait with a shingle or a piece of wood to keep it dry. Whatever method you use, fall is the time to begin a regular slug control program, before they ruin your plants.