5 Ways to Recycle Used Coffee and Turn it into Compost Gold

Composting coffee grounds
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    What does coffee contribute to compost?

    Coffee grounds add nitrogen to compost that leafy greens like lettuce love.


    But it’s not only nitrogen that coffee contributes. It also adds magnesium, potassium, calcium, and other trace minerals


    As waste matter breaks down, it becomes a rich, organic material to use as a fertilizer. The benefits to soil health are many. Improving water retention, drainage, and aeration. And there’s a healthy environment to encourage earthworms which themselves nurture a rich, dynamic soil that slowly releases nutrients.


    A combination of nitrogen, air, carbon, and water is the environment needed to create compost that will support the array of microorganisms that make this magic happen.


    And the good news is that there are many ways to recycle used coffee grounds.

    By the way, this article contains Amazon affiliate links. This means that I receive a small commission, (at no extra cost to you), if you make a purchase through links provided. Thanks for supporting coffeebrewinghub.

    Using coffee grounds to make compost

    Used coffee is considered a ‘green material’ despite it’s brown appearance. Coffee grounds sit alongside grass clippings, vegetable peelings and fruit scraps in the ‘green’ category.


    But to generate temperatures hot enough to produce healthy compost there has to be a balance of green and brown waste. 


    Brown materials like dry leaves, twigs, pruned woody cuttings, and newspapers are rich in carbon and provide the other side of the equation.


    Heat is the magic ingredient for producing compost. And it’s produced naturally from organic materials as they break down.


    Heat works in 3 ways.

    1. It speeds up the process to break down waste products, turning them into compost that feeds the soil to produce healthy plants.
    2. High temperatures destroy dangerous pathogens.
    3. Heat kill the seeds from weeds that have made their way into the compost through clippings.

    We aim for a 1:4 green to brown ratio. As kitchen scraps are added to compost, layer ‘brown’ waste over the top.


    Regularly turn compost to aerate and keep it ‘vital and aerobic’ as materials break down. 

    Compost bin

    How to make coffee compost tea

    If you don’t have a compost bin .. yet, coffee grounds can be used to make a liquid fertilizer for garden plants.


    Dilute 2 cups of coffee grounds in a 5 gallon bucket of water. Leave to steep overnight or at least for a few hours to make the ‘tea’.


    This can then be either added into a spray bottle to spray on leaves and plants or used as a liquid fertilizer for the soil.

    Worm compost coffee grounds

    Earthworms love coffee grounds. And they play an important role in nurturing soil health. As they move through soil they provide aeration and add rich nutrients via the castings.


    When compost is mixed with garden soil, an ideal environment is created to attract earthworms to the garden.


    Speed up this process and have your own worm factory. You don’t need to have a big garden. In fact, a small space on a patio is all that’s needed to recycle waste.


    Worm Factory 360

    Used coffee grounds can be recycled with organic kitchen scraps (fruit and vegetable peels) to feed worms.


    Layer the worm farm with damp newspaper. Add ‘green’ materials including coffee grounds regularly. (Cut scraps into small pieces). Worms make their way through the layers processing material as they go to turn it into beautifully rich fertilizer.


    The general rule of thumb is that worms can eat about 1/2 of their weight in food per day. For example, if you start with 1lb of worms, they can eat a 1/2 lb of food per day.


    What are worm castings?

    Castings from worms simply means processed matter excreted that creates an organic fertilizer. And worm ‘juice’ is an organic liquid fertilizer accessed simply by turning on the tap on the side of the worm factory.

    Compostable coffee filters

    Paper coffee filters are considered a ‘brown’ material in compost terms meaning they’re carbon-rich. Paper coffee filters break down easily in compost.


    Are white coffee filters compostable?

    Simply put, white filter papers contain bleach.


    There’s a school of thought suggesting that the bleach is removed to a large extent during the brewing process. Other research says some bleach remains. Honestly, I don’t know the answer. My preference is to use unbleached coffee filters for a drip filter machine.


    They’re the environmentally friendly option with less chemicals and a ‘brown’ material for safe composting.

    Compost coffee pods

    Can coffee pods be used for composting?

    The coffee grounds can be added to compost. Unless you have an entirely compostable pod, capsule components should be separated into organic matter and material to be recycled.


    Recycling Nespresso pods

    It’s pleasing to know that Nespresso capsules are manufactured from 80% recycled materials. And you can continue upcycling.


    Using a Coffee Pod cutter tool, separate the aluminum top from the cup. Scoop out the used coffee grounds and set aside for compost. The aluminum top and cup are recyclable with cans (not in the compost).


    What causes an unpleasant smell in the compost?

    These are the things to check

    • Are green and brown materials in correct balance?
    • Does compost need aerating (turning)?
    • Do you need to add dolomite?
    • Does compost need drying out?
    • Have animal products made their way into compost?

    Too much green material (nitrogen) in the mix can smell nasty. The mix of green to brown (carbon) waste has to be in the correct balance to facilitate the breakdown of materials. There should be 3 to 4 times more brown material as green.


    Brown materials include cardboard, newspaper, dry leaves, egg cartons and straw.


    Aerate compost

    Compost needs oxygen as part of the mix to break down waste materials. Turn the decaying matter over regularly with a pitchfork to stop clumping and keep compost vital and aerated. Regular turning encourages faster breakdown of matter.


    If you have a tumbler, turn it at least once a week – a couple of times.


    Add Dolomite

    Smell is an indicator that the ph of the compost is too much on the acidic side.


    Adding a handful of dolomite is effective to reduce odor. Known as a ‘soil sweeter’ Dolomite is alkaline so by adding it to the compost it raises the acid ph levels.


    The ph scale ranges from 0 to 14. O is highly acidic and 14 being alkaline. with 7 at neutral.


    To keep balance, think layering. Add a layer of kitchen scraps, then a thicker layer brown materials etc.


    Dry compost out

    If compost is too wet after persistent heavy rain it can cause a smelly problem. When the sun comes out, leave the lid off the compost during the day, for a day or 2 day to dry it out. Don’t forget to put the lid back on a night. The aim is to keep pests out of the compost.


    Green and brown materials only

    Fats and animal products may have made their way into the bin. Green waste only – coffee, fruits, vegs and brown waste like paper and cardboard.


    Don’t add processed foods, fats, dairy, meat, fish, pet poo, vegetable oils or animal fat.


    Brown materials help to control odor as their contribution helps waste breakdown faster. 


    Get the balance wrong and you’ll have unpleasant odor. 


    Do used coffee grounds have an acidic value?

    Even though fresh coffee grounds are acidic in nature, used coffee grounds are neutral and are close to a 6.5 ph. (6.5 is considered close to neutral.)


    This puts aside any concerns that coffee grounds should only be used near acidic-loving plants.


    Having said, plants that like an acidic soil like carrots and blueberries, and flowers like azaleas and hydrangeas especially enjoy the boost from coffee ground compost.


    Note:  PH is measured on a scale of 0 to 14 with 7 being neutral. 0 is highly acidic and 14 highly alkaline. As products move away from neutral (7) they become either more alkaline or acidic in value.

    Does caffeine affect compost?

    You my friend get most of the caffeine. The amount left over that makes it’s way into the compost is fairly low.


    Caffeine, generally speaking, is not good for compost or the garden. But used grounds are themselves diluted greatly and any traces of caffeine further diminishes with other matter in the compost bin.

    Can I add used coffee grounds direct to the soil?

    Yes, but!  Although coffee grounds release nitrogen into the soil and add organic matter, it’s not immediate.


    Used grounds need to be dug into the soil. If you were to simply add them to the soil surface, they can dry out and form a crust which prevents water and nutrients getting into the soil.

    Using coffee grounds to deter slugs and snails - good or bad?

    I haven’t used them in this way myself, and I’ll tell you why. I like the idea of an ‘organic’ barrier to deter pests but not so keen on having a ‘crust’ of coffee grounds around plants which can happen as the grounds dry out. A barrier is just that.


    My concern is that while deterring pests, I’m also preventing moisture getting down into the plant roots and the naturally occurring micro-organisms that I want to nourish plants. 


    Research shows that grounds can be used successsfully as a barrier around plants, protecting them and deterring pests that destroy plants. Perhaps I’ll give it a try, one day. For now I prefer to stick with improving the soil with compost.

    Eggshells and coffee grounds in the garden

    Used coffee grounds and crushed eggshells are a nutrient-rich combination of calcium and nitrogen, beneficial for improving soil health.


    Eggshells in compost

    Eggshells boost calcium in the soil. I’m a big believer in the benefit of adding eggshells to compost.


    Tip: Carnations love crushed eggshells in the soil near them if you grow flowers. That’s a tip passed down from my ‘garden-loving’  family.


    Tomatoes and peppers also like crushed eggshells as they can become calcium deficient as they grow.


    This is how to tell if there’s calcium deficiency in the soil

    Yellow leaves and weak stems are good indicators. And plant growth may be slower.


    How to make used coffee ground slow release fertilizer

    1. Wash eggshells and shake dry.
    2. Crush shells. (Crushing with your hand is fine.)
    3. Leave them to dry in a well lit space.
    4. Store in a sealed container.
    5. After brewing coffee, leave the grounds to dry out in a bowl.
    6. Store in a sealed container.
    7. Crush eggshells a little more. It will be easier when they have dried.
    8. Mix crushed eggshells with dried coffee grounds.

    In the growing season, sprinkle this combination where extra nutrients are needed. Think of it as a tonic for your plants.


    Don’t spread a thick layer or overdo it. Sprinkle a relatively small to moderate amount and then cover with wood chips or bark to retain moisture. As the eggshells and coffee break down, soil microbes are fed. This process can be repeated every few months.


    Enjoy your cup of Joe and watch the plants bloom with organic compost made from used grounds. The value of adding coffee to compost is immense. 

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