Contemplating Compost Accelerators

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Photo by Adobe Stock/coulanges.


Do compost accelerators work? I’ve heard that they speed up composting and result in better compost. Are these claims true?


Most independent studies have concluded that those products aren’t worth the expense. The three types of commercially marketed compost “accelerators” and “activators” are based on microorganisms, nitrogen, or herbs prescribed for biodynamic composting, and you can easily add any of those substances to your compost without spending money on a store-bought product. Dead plants, weeds, kitchen scraps, and the other biodegradable wastes that go into home compost introduce all the microorganisms needed for composting to proceed. If you like the idea of adding extra microbes to keep things moving swiftly, add a few shovelfuls of mature compost each time you start a new heap or batch.

When a gardener adds nitrogen to a lazy compost pile, the microbes take off, and their resulting population boom produces heat, which can help an almost-finished batch to finish faster. Free or cheap nitrogen sources, such as grass clippings, poultry manure, or alfalfa meal, will push a slow heap into high gear just as effectively as products sold as compost activators would — and they’ll be much less expensive, to boot.

As for herbal additions, some gardeners grow comfrey or stinging nettle to feed to their compost as “activators.”

Barbara Pleasant, gardener, and author of several books, including Homegrown Pantry.

Mother Earth Gardener
Mother Earth Gardener
Expert advice on all aspects of growing.