If slugs are a problem, remove their habitat by raking up your mulch in spring and composting it. Then, start your garden in open soil and wait until early summer to add a fresh blanket of mulch.
You still may have problems if your soil is well stocked with slug eggs. A few years ago, a U.S. Department of Agriculture scientist found that crabgrass contains a substance toxic to slugs. Since then, many backyard slug slayers have experimented with crabgrass cookies, which are made by mixing chopped, dried crabgrass leaves with corn bran, cornstarch and beer. Then, the baits are placed beneath plants, where the slugs eat them and die.
Another option is spraying coffee on plants that' are plagued with slugs. Caffeine in any form -- including a few No-Doz tablets mixed with water -- is a slug neurotoxin that will kill these unwanted pests.
When you're down to only a few slugs, you can fall back on the traditional organic control, which is to trap them with beer. Put an inch or so of any beer in a cup, bury it in the garden nearly to the rim and collect your drowned slugs in the morning. Or, put some beer in plastic drink bottles and lay them on their sides in the garden. The slugs will crawl in and drown. Dump them out and start over again every few days.