You only need to walk past a coffee shop in any American city to see that our country loves java. With so much coffee being consumed on a daily basis, it’s encouraging to learn that there is a productive use for all those grinds. Next time you make a cup, save your coffee grounds and add them to the soil in your garden. For best results, use organic coffee if you will be consuming the fruits or vegetables you fertilize. In case you didn’t know, approximately 60% of the worlds coffee beans are sprayed with potentially harmful pesticides.
Coffee Grounds as a Mulching Agent
Coffee’s breakdown materials can be used as a mulching agent, as well as a fertilizing agent, for gardens. Aesthetically, coffee grounds can be used to make elegant black borders in flower gardens. The rich blackness offers a beautiful contrast to colored flowers and green herbs. For best results, mix with other forms of organic mulch. When used alone, the coffee tends to create a rich sludge that prevents the necessary air and water to enter.
Coffee Grounds as a Compost Addition
Adding coffee to your compost or worm bin is a great idea. Again, it creates a nitrogen-rich soil result, and gardeners swear that worms fed with coffee will flourish. Researchers have also found that coffee grounds aid in keeping ideal temperatures in compost piles [1]. This allows compost to stay free of potentially harmful pathogens that effect delicate seedlings later.
Coffee as a Fertilizer
As a fertilizer, used coffee grounds are slightly acidic and full of nitrogen, a mineral that aids vegetable and plant growth. Coffee grounds are particularly good for tomato plants, which thrive on nitrogen. What is more, the grounds when used for planting, create a natural acidic form of bacteria, which boosts the growth of acid-loving plants like tomatoes, roses, blueberries and evergreens. According to The Composting Council of Canada, adding coffee to soil not only increases the nutritional value, but also betters the texture and fertility of the soil and aids in attracting earthworms [2].
Coffee as a Pesticide
Coffee-ground mulch has the added benefit of deterring veggie and flower-munching slugs and snails. There are also other organic pesticides that can also deter certain garden pests.
How to Use Coffee Grounds in Your Garden
For a quick fertilizing spray, dilute the grounds in purified water and spray directly on plants. Experts recommend using a half-pound of wet grounds to five-gallons of water. You can also directly sprinkle grounds into houseplant soil or in your outdoor vegetable boxes.
Where to Get the Grounds?
Most homes and offices have at least 1 coffee drinker, usually more. I recommend asking the person who purchases the coffee to start buying organic so people can recycle the grounds. This is an easy way to contribute to a more green world!
References (2)
- Oregon State University. Coffee grounds perk up compost pile with nitrogen. News & Research Communications. 3 Jul. 2008.
- Susan Antler. At Home With Compost. Compost Council of Canada.
Dr. Eddy Bettermann MD 
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