Julie, I cut them back in late fall but I do it later than most people so I can get most of the leaves from the birch trees. I remove all but about 3 inches of foliage (so I know where they are for spraying purposes) and rake everything up, no mulch or leaves anywhere, it is completely clean. The dead leaves or mulch can cause your hostas to rot, especially if you get a lot of rain in the winter.
My hostas are about 80% slug tolerant because of my need for a maintenance free garden. I water in the morning not evening to discourage slugs because by night time the surface dirt is dry. I will spray around the crowns after removing the foliage and also in the early spring with an ammonia solution (50%) It will kills any slugs that are hiding in crown and also dissolves the eggs.
(FYI)..I used the same solution on my daylilies to keep the slugs from eating my flowers. Once I discover that it is happening I will spray right into the crown and all around the outside of the crown. Some times I will spray everything if it has been raining a lot.
I knew about using ammonia on hostas but I read about using it on daylilies last spring. The lady in the article I read was actually using full strength ammonia on all her plants with out any harm to the plant. I was amazed, and I experimented on the cheap daylilies with a 10% solution, then 20,30,40 no problems what-so-ever. You can do your own experiment, you will be amazed how quickly slugs will disappear. I keep a bottle of ammonia water by the back door and when ever I see one I zap him!
You can add more mulch in the early summer to help keep them moist but consider the pine needles because the slugs cannot slide through them and the hostas seem to love the extra something that they put into the soil. I use this especially around the hostas that are not slug resistant.
The only other things would be compost and a good sprinkler. Happy Hosta Gardening!!
