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Ask Our Experts

Answers to your questions about gardening, energy, homesteading and other sustainable living topics.

Do Compost Accelerators Work?

Grass Clippings Compost 

I’ve heard that compost accelerators 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, simply 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 as effectively as products sold as compost activators would—and will be much less expensive, to boot.

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

Contributing editor Barbara Pleasant gardens in southwest Virginia, where she grows vegetables, herbs, fruits, flowers and a few lucky chickens. Contact Barbara by visiting her website or finding her on .