Slugs and snails are the number one pest on dahlias.
Steve uses two methods of natural pest control. Firstly, he advises using sheep’s wool or sheep’s wool pellets around the base of your dahlias to deter slugs and snails.
The key to using sheep’s wool pellets correctly is to use them thickly so that they create an almost impenetrable mat. I tried sheep’s wool pellets once. I scattered them thinly, as if they were conventional slug pellets. That didn’t work. You have to be generous with your wool or wool pellets.
The wool will slowly compost down naturally into the soil without causing it any harm. It will even help improve its ability to retain water.
If you live in sheep country, Steve suggests using the wool that gets caught in branches and fencing. Or presumably, you could buy some raw wool directly from a farmer or a farm shop.