Coffee Grounds And Composting

Coffee Grounds And Composting

When I was growing up, my grandmother’s daily coffee ritual included carefully emptying the spent grounds from the percolator into an empty coffee tin. Once a week during the summer, she would take the can outside and dump the grounds into the dirt around the roots of her hydrangea and azalea plants, then dig it into the surrounding soil. In the winter, the grounds got dug into the soil surrounding the roots of her potted flowering plants. Did I mention that my grandmother always had the most incredible flowering plants in town?

These days, as we get more ecology conscious, more and more of the people I know are turning to composting for their gardens. At Oregon State University’s Extension Program, they’re doing something more. Since 2004, collectors trained by OSU’s extension program have diverted about 200 tons of spent coffee grounds from 13 area coffee shops and kiosks. The coffee grounds are collected and used in the gardens of compost group members. The results, according to some of the gardeners, is nothing short of incredible.

Cindy Wise, coordinator of the Composting Specialist program at OSU says that the group has been conducting informal research since 2004. Among the things they’ve learned – coffee grounds are far better at maintaining high temperatures in compost piles than the more traditionally used manure. High temperatures, she explains, reduce potentially dangerous bacteria and kill seeds from weeds and vegetables in the pile. In addition, the addition of coffee grounds seem to attract earthworms and improve the structure of the soil.


Here are some tips on ways to use coffee grounds in and around your garden, taken from OSU and from other gardening experts.

1. Add coffee grounds to the compost pile. Coffee grounds, filters and all, break down to form a rich, organic soil when combined with kitchen waste and garden trimmings. They increase the nitrogen balance, making them an ideal substitute for lawn clippings.

2. Work coffee grounds into the soil around the drip line of your plants. They can be a slow release source of nitrogen that is neutral in pH balance. They’re especially nice for plants that like acidic soil like azaleas, camellias, rhododendrons and blueberries. Use them instead of nitrogen containing plant food or fertilizer.

3. Coffee grounds make a great soil addition if you’re raising earthworms.

4. Coffee grounds may be useful to reduce the ant population and to discourage snails.

5. Spread coffee grounds on the surface of your soil then cover with leaves or bark mulch.

6. Add grounds to your compost pile using one part each leaves, grass clippings, and coffee grounds. Turn once a week and use in three to six months.