Coffee Grounds In Compost: What Are The Benefits?

Adding the coffee grounds in compost from your daily cup of java is a wonderful eco-friendly way gardeners can add organic material for building a nutrient-rich compost soil. A compost that also includes yard waste, kitchen and foods scraps like fruits and vegetables as they break down.

used coffee grounds in compost to build the soilPin

Adding coffee grounds in compost (coffee compost) is an excellent choice as used coffee is rich in nitrogen. With a carbon to nitrogen ratio of 20:1.

Nitrogen, along with phosphorus and potassium, are the main nutrients in any successful fertilizer. The main role of nitrogen in plants is to allow them to convert sunlight into energy.

Compost can be the greatest gift for plants. It replenishes the nutrients taken from the soil. Along with food waste, grass clippings, green organic matter, and animal manure adding coffee grounds to a compost pile can be a great help and soil builder.

How To Use Coffee Grounds In Compost:

Composting coffee grounds along with adding paper biodegradable coffee filters (compost coffee filters) works a soil builder. The grounds acts as an alternative to the green organic material as it is rich in nitrogen. However, remember coffee grinds are not a nitrogen fertilizer. Buy biodegradable coffee filters here. Composting coffee filters that break down naturally are great!

The spent coffee grounds, brown in color, help to create a rich environment for the micro-organism living in the compost soil.

These microorganisms help break down the organic wastes in the composting process turning them into nutrient-rich organic matter. Add them to the compost bin by layering:

  • 1/3 fresh grass clippings
  • 1/3 leaves
  • 1/3 coffee grounds

Coffee grounds can also be added to worm composting bins. When combined with other kitchen waste, and organic matter coffee grounds help create a good compost soil for a vermicomposting bin, the compost made with the help red worms.

Spread coffee grounds on top of the soil and cultivate them into the soil. Another option is to spread the grounds on the soil as a mulch and cover with compost, leaves or bark mulch.

Coffee grounds can be used to create slug and snail barriers in the garden, shielding plants susceptible to slug attacks. You can spread them around your hostas, and other plants normally attacked by slugs.

Make sure to use caffeinated coffee as it is the caffeine that kills and deter slugs. Simply spread the coffee grounds to a height of 0.5-1 inch around the susceptible plant. Restock as necessary.

Chemical Composition in Coffee Grounds

Not everything contained in the coffee beans makes it to the refined coffee you consume in the morning. Nitrogen-rich proteins needed for plant growth comprise over ten percent of coffee grounds.

Since coffee is extracted in water, most of the oils, fatty acids, lipids, and triglycerides remain in the grounds.

Decomposition of Coffee Grounds in Compost

After several months, fungi and specialized bacteria break down the components of coffee grounds. Larger consumers such as earthworms are also able to use the chemical components of the coffee grounds.

Pushing the grounds deep into the soil, helps earthworms work as soil builders to improve the soil structure such as increased aggregation.

When fully decomposed, coffee grinds compost increases the pH of the compost soil, but the acidity doesn’t last for long. The compost also makes a nice compost tea to use in the garden.

More Ideas For Coffee: 

Effects of Coffee Grounds on Plant Growth

Coffee grounds are ideal for cultivating mushrooms, because of their antimicrobial activity. Coffee ground mulches and composts enhance the germination of sugar beet seed and also improve the growth and yield of soybeans and cabbage.

“Coffee grounds encourage the growth of microorganisms in the soil, which use nitrogen for their growth and reproduction. While the grounds are being broken down by the microorganisms the additional nitrogen in the fertilizer will provide a source of nutrients for your plants. source: OSU”

The high level of nitrogen in coffee grounds, as well as their mulching benefits such as increasing moisture in soil and moderating soil temperature, makes them ideal for almost all the plants.

However, it inhibits germination and growth of several plants such as alfalfa and red and white clovers seed. They also inhibit the growth of Chinese mustard and Italian ryegrass.

Related: Are Coffee Grounds Good For Grass?

What Is The Ideal Amount Of Coffee Grounds In Compost?

Though there is no optimal scientific recommendation for the amount of coffee grinds you should add to compost. However, on average a 10 to 20% of the total compost can be made up of coffee grounds. Over 30 % is considered detrimental.

Therefore, using no more than 20 percent by volume of the coffee filters and grounds in compost will ensure a diversity of macro-organism and microorganism. Remember, coffee grounds do not go bad, store them in a 32 gallon plastic trash can near your compost bin.

By using the above ratio of coffee grounds to compost materials, your soil pH should not rise to alarming acidic levels.

For a quick benefits list of adding coffee to compost check out the PDF via Oregon State University

Where To Find Used Coffee Grounds?

10 pound bags of used coffee grounds for composting at local Starbucks coffee shop - Jacksonville FloridaPin
used coffee grounds at the local Starbucks coffee shop – Jacksonville Florida

Most of us don’t drink enough coffee to meet all the uses for old coffee grounds in our garden. However, take a few minutes to drop by your local coffee shop. Many coffee shops offer bags of their used coffee grounds free for the taking.

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