Question: are burnt coals good for a garden?
Answer: Used Charcoal As long as you use an additive-free, wood charcoal, you can use it as fertilizer. The ash contains potash (potassium carbonate), which is nutritious for many plants. ... Don't use charcoal ash with acid-loving plants (like blueberries, azaleas and hydrangeas), nor newly planted seedlings and seeds.