Therefore the first line of defence against them is a covering of lime. This not only sweetens the soil but also tickles their sensitive tummies, which they don't like. Wood-ash and soot perform similar functions. Watering the soil with liquid seaweed also has an alkalising effect. Calcified seaweed meal has the additional bonus of tiny shells, which also deter slugs.
Slugs also dislike strong smells.
Many aromatic herbs, such as the various mints, tansy and balm, deter slugs and other pests and disease germs from attacking not only themselves but also their plant neighbours. A herbal mulch, consisting of sprigs of aromatic plants and conifer twigs, deters slugs and other pests' The best way to protect vegetable seedlings and transplants, I have discovered, is a herbal mulch, consisting of sprigs of aromatic plants and conifer twigs, which I spread between the rows. This not only deters slugs and other pests, but also screens the young plants from the wind, shades them from excessive sunlight and breaks the force of heavy rain. It also suppresses weeds and improves the soil, keeping it damp and preventing compaction. As it decays it feeds the young plants.