What do coffee grounds consist of and how do they work in compost?
I love composting; it’s genuine alchemy – turning waste into gardening gold. Making beautiful compost is deeply magical, but it’s relatively easy to learn how! If we merely maintain a good balance of ingredients and conditions, microbes will work hard to produce compost.
After finishing a morning cup or two of Out There Coffee, my pour-over contains a wonderous component. Coffee grounds make a great addition to almost any compost pile (link). In fact, drink all the coffee, because up to one-quarter of your pile can be made of coffee grounds.
Living things – including puppies, pansies, and people – are primarily made from just a few chemical elements. Two of the most important are carbon (C) and nitrogen (N) and maintaining the right balance of C/N is the foundation for perfect composting. That’s because microbes are hungry for both C and N. Too much C in your pile and decomposition will be very slow because the microbes don’t have enough N. Too much N and the pile will turn stinky and slimy. The ideal ratio is approximately 30 units of carbon to every 1 unit of nitrogen. Fortunately, there are several simple calculators to help you track your C/N ratio (link; link).
Get to composting
Coffee grounds are approximately 20-to-1 C/N, making them a green or more nitrogen-rich compost input, as opposed to a brown or more carbon-rich input. So, you can add your coffee grounds and shredded filter, directly to the compost pile. Mixing coffee grounds with shredded brown leaves, straw, and grass clippings makes a perfect compost combination. You can also think of your compost as a lasagna, with alternating layers of browns and greens.
I personally prefer to compost in towers (link) because I find this type of system helps me keep ideal moisture and aerobic conditions. Compost piles should have the moisture of a rung-out sponge and plenty of oxygen. The towers can also reduce investigation of your compost by pets, children, and wildlife. When it’s time to turn and mix compost – after 30 days or so – the mesh hoop can be pulled up and moved, so all materials can be mixed back into the same tower. Two to four rounds (composting speed depends on season) of tower movement and mixing results in a beautiful, finished compost.
Give it a try; help your garden and reduce materials sent to your local landfill. The EPA estimates that between 1/3 and 1/2 of all municipal solid waste is compostable! To read more about the secrets of perfect composting, check out Modern Farmer (link). I wish you all the best of luck, as you transform base materials into pure gold.
Adam researches mycorrhizal fungi in agroecosystems. He wants to help regenerate soils and protect our global environment. He also loves his dogs. Adam is currently supported by project no. OKL03144 / project accession no. 1019172, from the USDA, National Institute of Food and Agriculture (NIFA).