Short of grinding a snail under the heel of your shoe when you encounter it, here are a few other ways to eliminate snails in your garden :
1. One of the ways that I have personally used is the beer method. Yes, I said beer. Dig a small hole in your garden and place a plastic cup in it, with the rim at ground level and fill it with some beer. Snails are attracted to the yeast fermentation of the beer and will slide as fast as they can towards the sparkly gold mine. Most will drop into the cup and drown. Simply throw away the beer and refill it every one or two days.
2. Sand can also be used to line the perimeter of you plants as it tears their delicate bellies apart. It is like walking barefoot on crushed glass on the sidewalk. Thus, they will steer clear of your beloved plants.
3. If you have a lot of money to spare, you could purchase copper strips and lay them around your plants with each end being connected to the other. When snails try to cross the copper strips, they receive a delightful shock as electrical charges are stored by the copper. They will definitely stay away after that. Like the saying goes, once bitten, twice shy.
4. Furthermore, if you could always opt for the manual way which people who have a lot of time on their hands seem to do. Grab an empty bucket, slip on a pair of rubber gloves and pick snails from your plants who are happily chewing away. After collecting a bucketful of the slimy creatures, fill it with water. Leave it overnight with a lid on top to prevent any snails from getting out. Simply throw away the drowned snails the following morning.
5. Another way is to alter the time when you water your plants. As snails are nocturnal and they like dark, damp places; they usually appear around dusk, ready to munch contentedly away at your plants. Thus, instead of watering in the evening, water your plants in the morning so that the ground will dry out by the afternoon.
Reference : http://www.wikihow.com/Get-Rid-of-Garden-Slugs