The type of oyster shell that chickens eat is a good, safe, cheap and readily available slug repellent. Scatter the crushed oyster shell wherever slugs are a problem, or make a band around whatever needs protection.
Oyster shells are alkaline, so avoid this tip if you have alkaline soil (high pH), and don’t scatter oyster shells on or close to acid-loving plants, such as blueberries or azaleas.
Susan A. Mathis
Bishopville, South Carolina