HomeThe CSWD BlogFood WasteGetting Grounded: New Uses for Old Coffee

Getting Grounded: New Uses for Old Coffee

Person dumping coffee grounds in bin
Michaela from New Village Farm loading up her truck with used coffee grounds from the Starbucks at the Plaza on Shelburne Road, South Burlington. Michaela will grow oyster mushrooms in the nitrogen-rich grounds.

If you’re a coffee drinker, you’ve probably grown quite attached to the stuff in your mug every morning, having developed a deep appreciation for —and dependence on– this energizing supplement to your alarm clock. But you probably spend very little time reflecting on the usefulness of the coffee beans after they’ve imbued your beverage with caffeine and flavor.

Those residuals that you may dump in the garbage and call “waste,” others would be quick to consider a resource. “How can I possibly use spent coffee grounds?” you ask. Grab yourself another cappuccino, my friend, and read on! Include them in your compost bin. The compost bin is always a far better destination than the garbage can for used coffee grounds and other food scraps. The benefits of compost for soils and plants are legion: improved soil structure, better drainage and water retention, readily accessible nitrogen (rocket fuel for growing plants), natural pest and disease control, promotes healthy root formation.  

Tamp down food scrap odors. Spent coffee grounds’ physical properties make them an ideal “buffer material” in food scrap containers: The moist material is dense enough to stay in place and create an effective barrier to outgoing odors and incoming insects in a relatively thin layer. To the extent that any odors do escape, they’re masked by the potent javaroma

Use them in your landscaping. Expended grounds don’t need to be composted to be used around plants. Some people use them instead of mulch around landscaped flora. There are all kinds of claims in circulation — sources vary regarding which insects are most affected and why — but many gardeners are convinced coffee grounds help to keep pests like snails, slugs, ants, and even mosquitoes at bay.

Deter cats from doing their business. Many cat lovers — or their less feline-enthusiastic neighbors with gardens — insist that the coffee grounds they spread in their garden beds dissuade cats from using them as outdoor litter boxes.  

Grow your own mushrooms. Mushroom cultivators forgo the soil altogether and use pure spent grounds as a low-cost substrate for growing oysters and shiitakes at home.

Exfoliate your skin. The US beauty industry is no longer allowed by the FDA to embed plastic “microbeads” as exfoliation agents in their products. That’s a good thing! The filter of your Mr. Coffee contains a greener answer. With the right grind, spent coffee grounds are coarse enough to gently, exfoliate skin, and fine and pH-neutral enough to not irritate or over-abrade sensitive areas. One Green Planet suggests mixing them with a natural oil of your choice (e.g. coconut or olive) to make a simple but effective facial scrub, or even using them as hair treatment! Byrdie offers this recipe with directions for making a DIY coffee-based facial mask.

Scrub just about anything! These same scrubbing properties make coffee grounds a great material for getting just about any hard-to-wash-away residue off your hands.  There aren’t a lot of household substances that will survive a little soap in combination with a small handful of spent grounds and some vigorous scrubbing. The same goes for scorched on buildup on dishware or pots and pans: Coffee grounds serve as a natural abrasive that will scour off stubborn food residues without scratching most metals or enamels.  And your septic system — or the operators of your local municipal wastewater treatment plant — will appreciate this small amount of organic material instead of more potent and persistent cleaning chemicals. 

So much more! Other suggested applications include rubbing coffee grounds into scratches on furniture to blend the color and make the blemishes less noticeable, spreading damp grounds among fine dust or ashes to make them easier to sweep up, and spreading spent grounds on icy walkways for eco-friendly traction that nourishes your plants after the ice melts!

So, next time you visit your local coffee shop, remember to bring in your reusable mug and an empty bucket or other lidded container. Even if you aren’t a java hound, you can bring home a versatile, free resource while helping a local business put their “waste” to good use. With a little ingenuity, we can all help each other be out ahead of the food scrap management requirements kicking in on July 1, 2020.

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Ethan Hausman
Ethan Hausman