There are several slug control methods that can be used to get rid of slugs and stop them causing damage to your dahlias. These include creating a barrier around plants or pots through the use of copper tape, diatomaceous earth, crushed eggshells, or coffee grounds. Other common methods include using slug-repellent plants, beer traps, or attracting predators like hedgehogs, birds, or toads by adding wildlife garden ideas to your space. If you do use diatomaceous earth, aways use food-grade diatomaceous earth, which is available from Amazon