How to Use Coffee Grounds for Compost Piles

According to the Oklahoma State University Extension Office, coffee grounds work better than manure in composting to raise the temperature enough to kill weeds and pathogens.

Coffee grounds are simply ground-up coffee beans, a completely organic material, used as one ingredient in the composition of compost. The Washington State University Extension Office conducted a number of tests in 1995 on composting coffee grounds and found that this higher-nitrogen-based matter was best used as "green matter" with a consistency close to that of grass clippings in nutrient make-up. Mixing green matter with brown carbon-based matter such as sawdust, dried leaves, twigs, straw and shredded newsprint provides a well-balanced compost.

Things You'll Need

• Coffee grounds
• Coffee filters
• Compost bin
• Green matter such as grass clippings, fruit and veggie scraps
• Brown matter such as twigs, dried leaves, shredded newsprint

Instructions

1. Add coffee grounds after use to compost bin or pile. Coffee grounds in uncovered containers or piles draw flies and gnats, so keep open piles away from outdoor living spaces and doorways.

2. Layer brown matter into the bin each time you add green matter. Compost that is a close mixture of both green nitrogen-rich materials (such as veggie and fruit scraps, green non-diseased plant material, lawn clippings, coffee grounds and eggshells) and carbon-rich brown matter (like shredded newsprint, twigs, dried leaves, sawdust and animal manure from plant-eating animals) decomposes faster and more evenly.

3. Continue to add coffee grounds and other ingredients as needed.

Tips & Warnings

• Washington State University's tests also found that coffee grounds were an ideal food for vermicompost -- compost created by the castings of red-wiggler worms.

• Coffee grounds can be added directly into the soil as well.

• Coffee filters can be thrown right into the composter along with the grounds.

• Compost bins should be turned, moving the outer-edge materials to the inside every few weeks to allow for the heat built up by the methane gas to "cook" all ingredients evenly.

• Used coffee grounds can be saved for use as a soil amendment or added into the composter later. Mold may form but it will be destroyed with no incident in decomposition.

References

• Washington State University Extension: Composting Coffee Grounds
• Oregon State University Extension: Coffee Grounds Perk Up Compost Pile with Nitrogen
• University of Florida Extension: Compost Tips for the Home Garden

Resources

• Clemson University Extension: Composting