Can you compost coffee grounds

Can You Compost Coffee Grounds? And Are They Good for the Garden?

Many people worldwide enjoy a morning coffee to get the energy to kick start the day. Research shows that nearly 150 million Americans start their day with a fresh cup of coffee3. Due to this wide usage, people often throw coffee grounds away. When these coffee grounds reach landfills, they increase waste problems as decomposing grounds contribute to methane emissions. 

For a greener world, composting is a better solution for disposing of coffee grounds. Composting contributes to creating nutrient-rich soil for gardens. It also reduces one’s environmental impact and the environmental impact of our coffee habit. If you've ever wondered, “Can you compost coffee grounds?” You’ll find the answers in this article. 

Related: for the perfect eco-friendly brew for those grounds ready to compost, check out our guide to zero waste coffee alongside our rundown of fair trade coffee brands

Can You Add Coffee Grounds To The Compost? 

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coffee grounds
Photo by Devin Avery on Unsplash

With the right process, yes, you can compost coffee grounds. 

Coffee grounds are an excellent source of organic matter. They are high in nitrogen and also contain magnesium, calcium, potassium, and other trace minerals. 

Both fresh and used grounds can make up compost. Not only can you compost the grounds, but you can also add them directly to the soil to enrich the soil's nutrients. Also, they can prevent some garden insects due to their potency. However, adding coffee grounds directly should be done sparingly. 

What do spent coffee grounds contribute to your compost pile?

One of the main contributions is that coffee grounds are rich in nitrogen. This is one of the three main elements of a standard fertilizer. It has approximately 1.45 - 2 percent nitrogen. Nitrogen is essential for growing leafy and green plants like lettuce and shrubs. 

When considering what you can and can’t compost, you should note that there are two types of compost material: brown and green material. You need to ensure a balance of the green and brown material to have good compost. Coffee grounds, though brown, are a type of green material. Adding used coffee grounds and used paper coffee filters to compost provides green materials and brown matter, respectively. 

Adding used coffee grounds to compost requires no stress and is similar to how you compost other food waste. Simply throw the used coffee grounds into the garden pile or bin and mix thoroughly. 

How you add grounds to compost depends greatly on the amount of coffee grounds you have. If it's not in use in a large quantity, simply throw the used coffee grounds into the pile. However, when using large quantities, you must mix your grounds in the right proportion. Composting requires a 30:1 mix of brown or carbon materials and green or nitrogen materials by weight2. This ratio ensures that you create a healthy finished compost. 

What type of plants like composted coffee grounds?

People generally use fresh coffee grounds as compost for acid-loving plants. Some of these plants include carrots, hydrangeas, rhododendrons, blueberries, radishes, and azaleas, amongst others. 

However, you shouldn’t use fresh coffee grounds for seedlings or young plants because the fresh or unbrewed coffee ground is acidic and has high caffeine content. As a result, fresh coffee grounds can also lower the PH of the soil—some acid-loving flowers and trees such as caladium and magnolia benefit from fresh coffee grounds. 

Things to Note Before Adding Coffee Grounds to a Compost Bin or Garden Compost

We’ve established that fresh and used coffee grounds are good materials for composting, depending on the plant you want to use the material for. It’s also necessary to understand the role of coffee grounds before adding them to your compost pile or garden. The following are things to note before adding coffee grounds to your compost:

Coffee Grounds Deter Slugs

People have suggested coffee grounds as an organic method to repel slugs and snails in the garden. This comes from the knowledge that caffeine can kill slugs or slow them down, depending on the amount. Since coffee grounds contain only a little caffeine, the effects might not be as intense. However, using freshly brewed and cooled-down coffee can exhibit some effects. 

Used Coffee Grounds Are Not Acidic

Many people are concerned about whether used coffee grounds are acidic. This is because coffee itself is acidic, and some people understand that you should only add it to acid-loving plants. 

However, studies have shown that used coffee grounds have a neutral PH level. Since acid in coffee is water-soluble, its acidity mainly seeps into the cup of coffee itself and not the ground. Used coffee grounds are close to pH neutral, between 6.5 to 6.8 pH.

Coffee Grounds Are Not a Nitrogen Fertilizer

Coffee grounds are an excellent source of nitrogen. However, they are not nitrogen fertilizer when you apply them directly to your garden soil without composting first. 

Coffee grounds decompose and break down first in the soil and then release nitrogen into the soil. When using coffee grounds directly in the soil, add nitrogen fertilizer. They work together to improve the garden soil. In addition, the coffee grounds encourage the growth of essential microorganisms that require nitrogen for their reproduction and development. 

Coffee Grounds Add Organic Matter to the Soil

Coffee grounds improve the soil in different ways by making amendments to the soil. The material adds valuable organic matter that plants need to thrive. Further, organic matter enriches the soil and provides a source of slow-release nutrients to plants. 

Coffee Grounds Improve Aeration

Coffee grounds create tiny pockets in the soil, which helps keep the soil aerated. These air pockets make it easy for young roots to develop and access water and nutrients in the soil. Also, it provides roots with the oxygen they need for healthy growth. 

How Do You Compost Old Coffee Grounds? 

Composting coffee grounds is a beneficial way of utilizing something that would have otherwise ended up in landfills. This process further helps in adding nitrogen to the compost pile. 

Not only are coffee grounds compostable, but the coffee filters are also compostable. You can compost used coffee grounds by simply throwing them in the compost pile. 

There are various options for composting. The choice you adopt depends on the garden's size and the garden plant coverage. It’s also important to consider the quantity of the coffee grounds. The following are the methods to turn grounds into compost material:

Direct Application

Here, you add coffee grounds directly to the soil. This method is most efficient for smaller amounts of coffee grounds. Simply add the coffee grounds and mix well. However, avoid o adding the coffee grounds to the surface of the soil. If left as a layer on the surface, they dry out and form a caked layer on the soil's surface. This prevents water from penetrating the soil. 

Add Coffee Grounds to a Worm Bin

Even though coffee grounds can deter slugs and some pests, worms are attracted to them. When you add grounds to the worm bin, do so minimally and gradually to help the worms get accustomed to them and consider them in the mix of what worms eat. Moreover, using coffee grounds in a worm bin attracts earthworms to the soil when mixed with soil as fertilizer. 

Add Coffee Grounds to Traditional Compost Pile or Compost Tumbler 

When adding coffee grounds to a traditional compost pile or tumbler, remember coffee grounds are green compost material. In other words, you need to create a balance between the coffee grounds and brown compost materials like dry leaves and shredded papers. 

Add Coffee Grounds to Bokashi Composter 

Bokashi composting is a quick and effective method of turning coffee grounds and food scraps into high-quality compost in less than 4-6 weeks. Simply add the coffee grounds to the kitchen composter (on Amazon) every 1-2 days and sprinkle with bokashi bran. 

How to Include Coffee Grounds to Compost

Adding coffee grounds to compost
Photo by Alfo Medeiros

Composting coffee grounds and food scraps greatly benefit the soil and help reduce waste in landfills. Mix coffee grounds in small quantities directly to the soil while you can add larger quantities to existing compost. 

However, you need to balance adding coffee grounds (green material) with brown material in the compost. If there is too much green material, the compost begins to overheat and smell if too much green material. This can kill off beneficial microbes. Too little material and too many dry materials like shredded paper will prevent the pile from heating up. 

Composting requires a 30:1 mix of carbon or brown compost material to nitrogen or green compost material by weight and not volume. This ratio ensures there is enough nitrogen in the compost pile to decompose well. 

Add to the compost pile by layering the materials using one-third leaves, one-third fresh grass clippings, and one-third coffee grounds. According to research, a compost pile that is 40% coffee grounds produces fewer greenhouse gases1. It also tends to make the highest quality compost. 

Are Coffee Grounds Good for the Garden?

If you have a vegetable garden, you should know that coffee grounds are good for gardens. They have high nitrogen content along with a few other nutrients that plants can use. This places them under the green compost material category along with other green materials like grass clippings. 

Moreover, it adds organic matter to the soil, which aids drainage, water retention, and aeration. Avoid using too many coffee grounds and pay attention to the ideal ratio of materials. 

If you find your plants thriving after some experimentation, you can also see about acquiring free coffee grounds from your local coffee shop. If they don’t already have a set disposal method in place for their used ground coffee beans, most will happily see them go to an enthusiastic gardener, 

Can You Compost a Coffee Filter? 

Composting coffee filters is possible. In ideal cases, you can add the coffee filter and grounds to the compost bin. Including coffee filters in your compost bin depends on individual preference and the type of filter. Paper coffee filters are brown materials, meaning they are rich in carbon, an essential element in the carbon-nitrogen balance. 

The typical white filter, however, is bleached. It’s best to avoid this type when composting, as bleach is harmful to the soil. Instead, use natural unbleached paper filters. They are free from bleach or chemicals and serve as an environmentally friendly option. 

A prosperous soil needs a healthy carbon-nitrogen balance. Adding both coffee grounds and filters makes this achievable. Additionally, natural paper filters control unpleasant smells and increase oxygen levels in the compost pile. When adding coffee filters to compost, shred the papers to prevent a long breakdown process. Also, avoid adding too many at a time not to disrupt the balanced compost. 

Can You Compost K Cups?

A Keurig Cup is a coffee or tea cup with a sealed cartridge, generally a plastic cup. The cartridge has a plastic ring covered with a foil cup. The inside of the capsule has filter linen to keep the coffee while brewing. 

You can compost the used grounds and paper filter of the K Cup. To do this, you need to separate the main components of K Cups - filter paper, foil top, plastic cup, and coffee grounds. Use K Cup cutters made for this purpose to separate the components. Then, toss the filter paper and coffee grounds into the compost pile. 

Fortunately, some environmentally conscious companies now produce compostable K Cups from plant-based materials. In such cases, you don’t need to separate the components before composting. 

How Do Coffee Grounds Benefit the Soil and Environment? 

We’ve established that coffee grounds in the garden make an excellent soil amendment. Below, you’ll understand better how coffee grounds benefit the soil and environment:   

  1. In an ideal eco-conscious environment, composting, recycling, and using biodegradable materials are the norm. Since grounds are compostable, this helps to reduce landfill waste. In return, it helps in keeping a safe and healthy environment.
  2. Coffee grounds add organic matter to the soil. Organic matter enriches the soil with nutrients that aid plant growth. 
  3. Coffee grounds attract earthworms. Earthworms’ movements in the soil improve aeration and water filtration. They prevent the soil from forming compactly and make nutrients available for plant roots. 
  4. Coffee grounds add nitrogen to the soil. As coffee grounds decompose, they release more nitrogen into the soil.
  5. Coffee grounds add phosphorus and potassium to the soil. These elements also aid healthy plant growth. 

What are Other Uses of Coffee Grounds? 

Apart from using coffee grounds as compost or organic fertilizer in the garden, the following are some creative ways to use coffee grounds. These will help you reduce waste within the home. 

  • Growing mushrooms in coffee grounds. 
  • Using coffee grounds as natural air fresheners for homes.
  • Using coffee grounds for scouring and scrubbing kitchen utensils.
  • Using coffee grounds as skin exfoliators.

Conclusion

Composting coffee grounds is an excellent approach to reducing landfill waste. If you have a garden, this process also helps improve the garden soil's condition. You can compost using various methods, as highlighted in the article.

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Pin Image Portrait Can You Compost Coffee Grounds? And Are They Good for the Garden?

1

National Library of Medicine (2017, January) Effects of Different Rates of  Spent Coffee Grounds on Composting Process and Gaseous Emissions

2

Cornell Waste Management Institute (2022, February) Compost Chemistry

3

 Statista (2019, October)  Coffee Statistics

Jen’s a passionate environmentalist and sustainability expert. With a science degree from Babcock University Jen loves applying her research skills to craft editorial that connects with our global changemaker and readership audiences centered around topics including zero waste, sustainability, climate change, and biodiversity.

Elsewhere Jen’s interests include the role that future technology and data have in helping us solve some of the planet’s biggest challenges.

Photo by Engin Akyurt
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