When it comes to slugs and snails I find the best thing I use is crushed egg shells thickly placed aroudn the plants as the sharp edges of the shells deter teh snails.

If you want to kill them then put a ring of salt around the vegetables/fruit area that you dont want the snails to cross...(but not too close as some plants dont like salt). If using this method make sure no snails are left inside the ring.

Try a beer trap... I'm not sure how this works but maybe another grape can clarify this for you.

Using the above methods makes sure you're not poisoning the food of hedgehogs. They love snails and slugs.

There's a point though.... get a whold load of hedgehogs as pets to control your garden/plot.
Hope this helps.

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