If you see ragged holes in leaves with no pest in site you may have slugs. Slugs thrive in moist area such as around dripping water spigots and irrigation heads. They also live under pots, greenhouse trays, rocks, and shady landscape nooks. The ragged leaf holes will usually be accompanied by iridescent slime trails. Management of slugs begins with making the habitat less suitable for them by reducing moisture, decaying vegetation, and debris or pots they can hide under. Of course reducing pots is not an option at nurseries so there are some baits that can be broad cast in slug prone areas.
These include products containing metaldehyde or methiocarb (Mesurol) which are carbamates toxic on contact or ingestion. These products are also toxic to pets and children so baits should be inconspicuous and sprinkled over the area rather than arranged in piles that pests and children will notice. Iron phosphate (Sluggo) also has good efficacy against snails and slugs. It also has less mammalian toxicity. In home gardens and even in small greenhouses it is possible to pick slugs from under pots and trays to reduce their abundance. I have gone out on my patio several nights in a row to pick slugs and found the abundance went way down.I found two great articles on slugs and slug management.