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Freshly Brewed Compost: The Benefits of Composting Coffee Grounds

Posted November 11, 2020

Did you know that drinking coffee could benefit your garden and enrich your compost pile? Let’s dig in to see how coffee grounds go from that ‘Cup of Joe’ to your luscious gardens—all while diverting organic waste from the landfills.

The Benefits of composting coffee grounds

According to The National Coffee Association and The Specialty Coffee Association of America, “Americans consume 400 million cups of coffee per day, making the U.S. the leading consumer of coffee in the world.”

coffee compostCoffee grounds are a great addition to your compost pile because they are an excellent source of nitrogen. If you’re not a regular coffee drinker, you can ask your favorite local coffee shop if they are willing to give you their used grounds from the day.

If you prefer to enjoy coffee brewed at home, unbleached, paper coffee filters are an ideal carbon source for your compost pile. For best results, tear the filters into smaller pieces before adding them to your compost pile. You can also use a compost turner to shred the filter as you incorporate it into your compost. 

coffee grounds are a source of nitrogen

Do not let the brown color of coffee grounds fool you into thinking they are a “brown” additive for your compost pile. Coffee grounds are a nitrogen-rich “green”, while “browns” are carbon-rich materials like leaves, sawdust, hay, and paper.

For composting with the GEOBIN Composter, your pile should consist of the following combinations:

  • Air + Water + Carbon + Nitrogen = Compost
  • 1 Part Greens + 3 Parts Brown + Water

coffee grounds are a great addition to your garden

Coffee grounds are a great source of nitrogen, phosphorus, and other trace minerals for your compost pile. The nitrogen assists with seed germination and plant growth, while the phosphorus can help improve the overall composting process. (Compost piles made up of mostly yard waste and food scraps tend to be low in phosphorus.)

There is a perception that coffee grounds are too acidic for composting. The truth is coffee grounds are highly acidic but easily manageable–experts recommend no more than 20% of your total compost volume should consist of coffee grounds.

Plants that Prefer Acidic Soils

daffodilSince only 20% of your compost pile should consist of coffee grounds, you can always use extra coffee grounds in your garden and around plants that prefer acidic soils.

There are acid-loving plants like hydrangeas, and daffodils, so adding a sparse amount of coffee grounds to the soil around them will help them flourish. To select the color for your blooms, typically, more acidic soil with a pH lower than 6.0 will produce blue blooms. An alkaline soil with a pH between 6 and 7 will produce more pink or purple blooms.

How to Add Coffee Grounds to Acid-Loving Plants:

  1. A recommendation by many gardeners is to rake coffee grounds into the existing soils—making for a healthy soil amendment.
  2. If layering coffee grounds on top of existing soil is preferred, add a ½-inch layer or less of coffee grounds–more than that could crust over, keeping water and air from the root system.
  3. Keep coffee grounds off leaves and other yard waste—so they can penetrate the soils.

Coffee Grounds are for the Worms

As it turns out, earthworms enjoy coffee grounds. If you favor vermicomposting, sprinkle some grounds into your container to keep your crawlers happy.

Healthy soil supports earthworms who, in turn, offer better drainage, make the soil more absorbent, increase nutrient availability and improve soil stability. They feed on organic matter in soil and leave behind valuable castings.

So the next time you enjoy a cup of coffee, share your joy with Mother Earth and relax in your exquisite garden.