Slugs and snails can be destructive to many flower and vegetable gardens, as well as unattractive to look at. If the dahlias in your garden have ragged holes in them, there’s a chance you these common pests have visited your garden. Slugs and snails are easily killed by poisoning or crushing them, but you must employ several methods simultaneously to keep them from taking up permanent residence in your flower garden.
Adjust your watering schedule. Slugs are most active at night. Watering your garden in the evening keeps it moist at night, creating an environment that is favorable to slugs and snails. Water your garden earlier in the day so that it dries before nightfall.