Slug control on Hostas

I've just applied garlic spray to my hosta pots for the second time this year. First time there was no sign of growth, and just a few tips sticking through this time. I'm hoping that early spraying will stop slugs getting at the new tips. There was some damage visible on a couple as they grew last year, so they must have been attacked early. Garlic spray is the only thing I've found which is reasonably effective. It's not preventing all attacks but cut them a lot.

 

Could try smearing petroleum jelly/ vaseline around the rim of the pots.
Last year we had a terrible time with slugs because of the mild and wet winter, at the moment haven't seen any, last year they ate the daffodil flowers and cosmos.

 

I've seen (and squashed ) plenty of the little grey/black ones already. They seem to nestle in the grooves in the base of plastic pots