How can I control Slugs and Snails
Personally I prefer to avoid the use of chemical pesticides where possible. I have found nematodes, a biological control agent, to be effective. Applied in the spring when the weather starts to warm up and again later in the season, this will substantially reduce the slug population. Unfortunately I have found nematodes to be less effective against snails.
Slugs pellets work if used properly and responsibly. I prefer metaldehyde based pellets which are effective when used in small amounts. They should be scattered thinly around the area so that pellets are about 10 inches apart. Scientific research has demonstrated that if a slug is within 10 inches of a pellet it will go after the pellet. Applications should start in February before the shoots are visible as this will reduce the overwintering population. The pellets remain effective for just a few days so apply a very few more pellets if required.
Hostas grown in pots are less troubled by slugs and snails and this can provide the solution for those that have had serious problems. There are a number of ways that slugs can be prvented from reaching our Hostas:
WD40 applied as a band around the middles of the pot is unlikely to be crossed by slugs.
Vaseline. A band applied around a pot will act as a barrier.
Water. Place a potted Hosta in a shallow saucer of water. Slugs can’t swim and the water provides a reservoir in hot weather. Avoid waterlogging at other times by raising the pot out of the water on some blocks.
Any thing rough or irritant placed around hostas will deter slugs and snails Grit, stones bark chippings sheeps wool all help.