Recycling coffee grounds is becoming more popular in the Chattanooga area. Master Gardeners of Hamilton County collect grounds in five-gallon pails from several local coffee shops for use in community compost piles. Recycling fosters “green” interactions between residents and businesses. The coffee grounds stay in their communities, literally. This also means that fuel isn’t being used to truck them to landfills. Using this valuable compost ingredient and soil amendment makes sense economically and environmentally.
Coffee compost
Coffee grounds can be an excellent addition to a compost pile. They have about 2 percent nitrogen by volume, about the same as grass clippings. Coffee grounds also can be a safe substitute for nitrogen-rich manure in the compost pile. Coffee grounds help to sustain high temperatures in compost needed to kill weed seeds and reduce pathogens.
Contrary to some reports, coffee does not make compost acidic. After brewing, the grounds are close to pH neutral, between 6.5 and 6.8. The acid in beans is mostly water-soluble, so it leaches into the coffee we drink.
The pH of decomposing coffee grounds is not stable. We shouldn’t assume that it will always, or ever, be acidic. The microbes that do the composting will usually turn the coffee from acidic to a neutral pH.