Compost Pile – Fireplace Ashes

Q: How much fireplace ashes should I use on my compost pile? Will ashes make it break down faster? 

A: You should not add ashes to a compost pile. Something that seems such a simple process (piling up garden trimmings to rot) is pretty complicated chemically. The different microorganisms that chew up your lawn clippings and weed stems prefer different amounts of acidity in the pile. Ashes decrease the amount of acid, which may inhibit microorganism activity and slow down the whole process. Rather than adding them to your compost heap, spread the ashes onto your lawn. You can scatter 20 pounds per 1000 square feet with no problem. The ashes perform the same service as garden lime. To make sure you are adding the right amount of acid neutralizer, have the soil tested by the UGA Soils Laboratory. Details at

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