Wood ashes may help keep slugs and snails away.

Wood ash can raise soil pH and supply small amounts of nutrients, and its abrasive texture and soluble salts are reported to repel slugs and snails.

Wood ash from fireplaces and fire pits is often reused in gardens. It can raise soil pH and add small amounts of potassium, phosphorus and other nutrients. The ash's abrasive texture and soluble salts are reported to harm and repel slugs and snails. A 2020 Applied Sciences article reported that ashes from beech, oak, fir and spruce showed stronger protection against Spanish slugs than ashes from hornbeam, chestnut and black alder. What is known: - Wood ash can alter acidic soils and provide minor nutrients such as potassium and phosphorus. - The abrasive texture and salts in ash are reported to deter and dehydrate slugs and snails. - A 2020 Applied Sciences study found beech, oak, fir, and spruce ashes offered stronger protection against Spanish slugs; hornbeam, chestnut, and black alder ashes were less effective. - An ash barrier that fully encircles vulnerable plants is described as a practical deterrent, and its effectiveness is reduced after rain when salts are washed away. - The article notes wood ash is not recommended for use around acid-loving plants and should be avoided on soils with pH above 7.0. Summary: Reusing wood ash can change soil chemistry and act as an organic deterrent to slugs and snails in some cases. The article reports that effectiveness varies by wood type and that reapplication after rain and consideration of soil pH and plant acidity preferences are commonly mentioned factors.