On Sunday, 14 August 2016 10:53:04 UTC+1, Paul Luton wrote:
Shortly after being planted out a lot of my cosmos plants wilt.
Investigation shows that the outside of the stem has been removed -
other sources suggest snails as the culprits (possibly looking for
moisture).
Slug pellets don't seem to provide any protection. Has anyone found a
solution ?

In my experience they need to be welll hardened off or the slugs and snails will eat them. I have planted out too soon and they are eaten.