For anyone interested in keeping slugs and snails at bay...we tried the Homeopathic remedy Helix Toasta with fantastic results.
No snails here but we had heaps and heaps of slugs and after applying the Helix Toasta we had none for months after.
It lasts for up to 4 months and it doesn't kill or trap them it simply deters them and so they just don't go in your garden at all....they still loved the stack of bricks next to our garden but they just stopped munching on everything in the garden 😀
I only know where to get it in Australia which is from http://homeopathyplus.com.au/?cat=16

