I fell ill the first weekend of the year, and was home for a few days. I decided to let the fire burn down in our ever-lit fireplace so I could clean out the accumulated ash. Trudging back in from a brambly bit of wood where I toss the stuff so one can’t see it from the house or garden, I wondered if I had just wasted a valuable soil amendment. Don’t people spread ash all over their garden, I wondered, as some sort of nutritional plant supplement? I seemed to remember accounts galore supporting the practice.
Instead of spending the day burning logs and then spreading their remains, I made the sane decision to ask our contributing editor Linda Chalker-Scott about ashes in the garden. Here’s her sobering explanation, for all you other eager beavers with a fireplace:
There’s a lot of research looking at ash as part of a compost pile or soil amendment. It’s fairly alkaline, so you have to be careful about using very much of it directly on soil. Ash is quite variable depending on what the parent material was, how hot it was burned, and for how long. Thus, there aren’t any really good guidelines except to be moderate. I would use a rule of thumb of no more than 20% ash by volume in your compost pile, and I would probably not use it directly on top of soil. You could, however, put it on top of a wood chip mulch, as the acidity of that mulch would help neutralize the ash alkalinity.
There you have it!