Remove slugs and snails by hand. During the day, check underneath your hostas thoroughly, they’re favourite hangouts for snails. By night, use a flashlight and follow their shiny trails to find them.
Spread natural or agricultural-grade diatomaceous earth over the soil in flower beds or around individual plants. The tiny, sharp-edged granules cut the soft-bodied slugs and cause them to dehydrate. Reapply after each rainfall.
Install barriers of 2-inch or wider copper stripping around plants and flower beds. Do this only after you have removed all slugs and snails from inside the area, because the slimy pests won't cross copper and will be trapped inside to munch away.
Position ceramic flowerpots upside-down to trap snails and slugs that will accumulate there to rest in the shade. Overturn them and remove the snails daily until the infestation is exhausted.
Set yeast traps in troublesome beds. Sink a shallow jar or store-bought trap so the top is flush with the ground. Fill the traps with beer - regular or nonalcoholic - to 1/2 inch from the top and wait for the snails and slugs to fall in and drown. Check the traps every few days.
For those of you who can't imagine wasting beer on snails, try this home brew: Add 1/2 tsp baking east and 1 tbsp. sugar to the water in each trap.
Minimize the moist and cool spots in your garden, such as woodpiles and empty flowerpots, which slugs and snails need to survive sunny days.
Copper Foil Slug Tape
They like leaves that are beginning to wilt, so if you do some weeding, leave the weeds around for a few days as the slugs will eat those first. Use local mulch as much as you can - slugs love wet leaf mulch, and are far happier staying in the damp and eating dead leaves than venturing into the open spaces in your flower beds.
Toads are a good natural predator. Nurture your toad population!