Organic gardening is a method of gardening that uses no synthetic chemicals or fertilizers. Everything used comes from a naturally occurring source. Examples of nutrients would include such things as manures, rock phosphate, compost, bone meal, ashes, etc. Pest control is maintained by using traps, predators, parasites, plant extracts, and other naturally occurring material. Prevention means protecting plants by placing them in a uninfested area, or on benches that have a barrier around the legs.
Predators can include ducks, geese, chickens, other birds, or even cannibalistic snails.
There are a number of traps you can try. One inexpensive plastic bowl with a snap on lid to keep the bait from the weather, is available in local garden shops. Traps generally rely on a bait that attracts the snails or slugs to the trap. Often these baits stuns or intoxicates the slugs and snails, entrapping them. One simple trap is a plank or board laid flat on the soil surface.