Can smokeless coal ash go on the garden?
Do not add ash from smokeless coal, coal or anthracite to garden soil or compost.
Coal ash is different from wood ash
The RHS advises that coal and anthracite ash has little or no nutritional benefit, may harm soil and plants, and could contaminate edible crops. Advice about using clean wood ash does not apply to coal ash or mixed-fuel ash.
Dispose of it through the correct waste service
Let ash cool completely and follow your local council's instructions for solid-fuel ash disposal. Do not put hot ash into a bin or use it in the garden.
Further guidance
Read the RHS guidance on wood ash and solid-fuel ash. If your fire has burned a mixture of fuels, do not assume the ash is suitable for compost or soil.