After your morning coffee becomes a happy memory, do the spent grounds languish in a landfill, add nitrogen to a garden or transform into energy (and we’re not talking about the coffee drinker’s energy)? It all depends where you get your fix.

With the support of commercial pickup services and customers who garden, Maine coffeehouses and roasters have found creative ways to keep the fluffy chaff and those buckets of steaming used grounds out back from adding to the waste stream. Many proprietors are home gardeners who cite an enthusiasm for doing right by the environment as the reason they strive to make their businesses green. Though some lack the space or budget for commercial compost pickup services, all agreed that a consistent, reliable disposal plan for the byproducts of coffee-making is key.

Collecting the spent grounds at Wild Oats in Brunswick. The grounds get mixed with other food waste and picked up by We Compost It!, which turns them into compost. Alison McConnell photo

Over three decades’ brewing, Wild Oats Bakery & Café of Brunswick has tested many ways of disposing of its spent coffee grinds: “Pig farmers, worm composters, gardeners, commercial anaerobic digesters and commercial composters,” owner Becky Shepherd said.

Today, the bakery sends grounds with other food scraps to We Compost It!, an Auburn-based company that makes 350-400 pickups a week in the region, then sells its finished compost to organic farms, and retail and wholesale garden centers. We Compost It! general manager Bill Crawford said the company counts among its customers many Dunkin’ Donuts franchises, independent cafés such as Bard Coffee in Portland and Elements: Books Coffee Beer in Biddeford, and some Holy Donut shops.

Typically mixed in with other food scraps before being turned into compost, coffee grounds supply organic matter for microbes to feed upon, some nitrogen that will become available to the plants during decomposition, and small amounts of micronutrients, according to Caleb Goossen, crop and conservation specialist with the Maine Organic Farmers and Gardeners Association.

Scraps to soil


Garbage to Garden’s 15-truck, Portland-based fleet picks up at 10,000 residential and commercial addresses each week in Maine and Massachusetts, including about three dozen coffeehouses and cafés. It works with partner farms to turn its kitchen scrap haul into nutrient-rich soil that eventually powers vegetables, fruits, herbs and flowers at its customers’ gardens.

“Many of our participants are passionate about gardening, and receiving finished compost … is an important aspect of our service,” Garbage to Garden marketing director Annika Schmidt said.

Portland’s Tandem Coffee Roasters uses Garbage to Garden at its bakery and Agri-Cycle Energy at its roastery, according to co-founder Will Pratt. Scratch Bakery Co. and its offshoot, Toast Bar – both closed temporarily – also work with Agri-Cycle, said Scratch co-owner Bob Johnson. Agri-Cycle’s anaerobic composting techniques generate biogas, which, in turn, is converted to power and heat.

Coffee shops estimate that each day they generate as little as 10-15 pounds of spent coffee grounds in the slower winter season and as much as 100 pounds in the summer.

“I just can’t believe how much we would be throwing away if it weren’t for the amazing local composting companies we have around here,” Pratt said. “We really count on them and sure don’t take them for granted.”

Kate Pinard, owner of Elements in Biddeford, says composting spent coffee grounds is “just the right thing to do.” Shawn Patrick Ouellette/Staff Photographer

Elements co-owner Katie Pinard concurs. “We love the service, and the cost is worth it to us,” she said of We Compost It!, which costs her some $68 a week.


“Choosing to compost in-store has also caused us to take the initiative to make sure all of our paper supplies and to-go containers are compostable, which we’ve done gradually over time,” she said, “and our customers have voiced appreciation for these efforts. The amount of organic material we generate is an enormous physical weight to redirect from the landfill stream to the compost stream, to say nothing of its contribution to local soil health on the back consumer end. It’s just the right thing to do.”

A few blocks east, Time & Tide regularly fills customer containers with the day’s spent grinds, and may start sending grounds to a local community garden, thanks to a regular who coordinates the space. Many independent coffee shops, such as Yordprom Coffee Co. in Portland’s West End, also freely give spent grounds to customers. Even Starbucks has been in on the game for more than 25 years with its Grounds for Your Garden program. Just ask nicely and nab a big bag of grounds, any time.

But don’t simply dump them in your garden heedlessly. “I would advise against adding (the grounds) directly to soil that someone was about to direct-seed into, as they have some potential to inhibit, or negatively impact, seed germination,” MOFGA’s Goossen cautioned.

Separating the beans from the chaff

The chaff, a byproduct of coffee roasting, is collected at Portland’s Coffee By Design. Photo courtesy of Coffee By Design

In addition to spent grounds, coffee roasters generate another waste product – chaff, the “silver skin” of coffee, akin to a peanut’s papery covering, which comes off during the roasting process.

Time & Tide co-owner Jon Phillips said a UPS delivery person who is an avid gardener picks up chaff every few weeks for garden mulch. At the Kingfield-based Carrabassett Coffee Company, “We have three different folks swing by periodically to grab a truckload of it” for compost, said the company’s Jared Frigon, estimating that the roaster produces 60-90 pounds of chaff per week.


At microroaster 44 North Coffee on Deer Isle, the staff uses the odor-absorbing material in worm bins, outhouses and chicken coop laying boxes. “Chaff is so high in nitrogen,” co-owner Megan Wood said. “It’s an awesome material, really soft and warm – the hens love it.”

Portland-based Coffee by Design gives both chaff and grounds directly to local farms and community gardens. Likewise, Downshift Coffee in Belfast brings brings its spent grinds directly to Daisychain Farm, also in Belfast, where they nourish the farm’s strawberries, raspberries, pumpkins and apples. Consistency is key to the success of such programs, according to both proprietors.

Spent grounds at Downshift Coffee in Belfast are brought directly to Daisychain Farm. “You don’t want to suddenly find yourself with 300 pounds of grounds and nowhere to go,” said Downshift owner Nathaniel Baer. Nathaniel Baer photo

“You need to be able to work the logistics so you’re rotating out every day in the summer,” Downshift owner Nathaniel Baer said. “You don’t want to suddenly find yourself with 300 pounds of grounds and nowhere to go.”

Coffee by Design co-founder Mary Allen Lindemann agreed: “Zero-waste is the goal. We’ve always felt strongly that farmers have enough expenses already. It does get tricky… If people don’t pick up in a timely manner, it molds.”

When composting is not an option

Some coffeehouses dump grounds with their regular trash, citing obstacles to composting: small spaces, logistics and the cost of commercial pickup services. Even with such challenges, there are ways to at least minimize what goes into the waste stream.


The internet suggests spent grinds can become “coffee coals” to fuel a grill.

In Bangor, Wicked Brew co-owner Carrie Holt tosses spent grinds on the city’s icy sidewalks for a paw-friendly salt substitute.

And there are garden uses short of compost. Some anecdotal evidence suggests that the grinds deter slugs and snails, MOFGA’s Goossen said: “I would suggest that the effect – if present at all – would probably be strongest with fresher grounds, and would likely fade quickly as rain and general decomposition reduced the aromatic compounds present in the grounds.”

Spent grinds can also be directly incorporated into soil as a light mulch around established plants. Doing so won’t have a big effect on soil pH, Goossen added, despite “myths” online. “The impact would likely be almost completely unnoticeable,” he said. “Most of coffee’s acidity is leached out into the coffee itself, and the grounds likely end up with a nearly neutral pH after decomposing, regardless of the starting pH.”

Alison McConnell is a writer, musician, artist and novice farmer who lives in Auburn.

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