What can I use coal ash for?
I would NOT recommend using coal (fly) ash on any plants in your garden. According to Scientific American*, coal ash contains toxic metals such arsenic, lead, mercury, and selenium, as well as aluminum, barium, boron, and chlorine. Although some would claim that using coal ash is an organic practice, I would just ask one question, “Do you really want to injest any quantity of toxic metals in your diet?” All my research indicates that the only “safe” way to recycle coal ash is by locking it in concrete as a replacement to Portland cement. If you choose to go this route, I would be sure to wear some type of mask to avoid breathing in the dust. Maybe you could make stepping stones for your garden.
*http://www.scientificamerican.com/article.cfm?id=coal-ash-in-soil
If you use natural coals from hardwoods, you would be fine. The ash is a great slug reppellent when placed around the base of hostas and cabbage plant families. It adds ph to soil when mixed in. https://www.washingtonpost.com/lifestyle/home-garden/the-benefits-of-wood-ash-in-the-garden/2012/03/18/gIQAVBSEgS_story.html
