For the past few months, I have been recycling coffee grounds from our favourite local cafe. The grounds have been used in the gardens as a light mulch, a top-dressing (hoe in) and in the compost. Tomato, my favourite vegetable to grow, really benefits when mulched with coffee grounds. Here are some ideas on using coffee grounds for your own home garden. Now we have the best of both worlds; greater quantities of Fair Trade coffee grounds and a garden always requiring mulch.
Seven Uses of Coffee Grounds in the Garden
- As a mulch for :
- Blueberries, fruit trees and strawberry plants
- Tomatoes, peppers and eggplants (of the nightshade family) benefit from coffee grounds
- Squash, corn and greens, such as spinach do well when mulched with coffee grounds
- Azaleas, camellias, evergreens, Hydrangea, roses and rhododendrons benefit
- Grounds and filters are an excellent addition to your compost
- Grounds, along with other organic material, help to keep down weeds when used as a mulch
- Garden worms thrive on coffee grounds in the compost and soil.
- It may work as a slug deterrent (not kill them) and ant repellant
- Grounds seem to discourage wild rabbits (which are in our back yard daily) from eating the lettuce, etc
- A 2 " layer of grounds was placed in two garden areas as a cat deterrent. It has been several months and so far no visitors. Renew with fresh grounds as needed.
Photos from Backyard worm farm in Victoria, Australia
Benefits of Using Coffee Grounds
- Coffee grounds contain up to 2% nitrogen and 1% phosphoric acid, minerals & trace elements (Rodale)
- May be beneficial in deterring wilt (a plant bacterial disease) Fusarium or Verticulum. Unable to find research to back this statement but using a non toxic and natural remedy is well worth a try
- Best used as a soil additive, in the compost, or as a mulch in the garden
- Filters can be recycled in the compost
How to Apply Coffee Grounds
- Soil enhancer - I cover the soil with a thin (½ - 1"0 layer of grounds and work it into the top 3 - 4" of the soil with a hoe. I also mix it with fresh grass clippings and compost if available
- Compost - the coffee filters and a small amount of coffee grounds are used as a thin layer when composting kitchen scraps - usually on top of the kitchen waste and covered with a layer of soil, followed by organic chicken manure, shredded paper, leaves and other green material including grass clippings
- As a mulch - I use a ½ to 1 inch layer around plants such as tomatoes, mainly in Spring
Take care to not use large amounts of coffee grounds (more than 20%) at one time in the compost, as it may deter the growth of some of your flowers and plants
- Coffee grounds on the garden are not a new idea but it has been a challenge to get larger quantities for regular use. History of Coffee
- Grounds decompose more quickly when dug into the soil
- Drip coffee grounds are richer than boiled coffee (Rodale)
- Using grounds in your home garden, keeps them out of landfills, which in turn improves our environment by not producing as much methane gas
- A staggering amount of coffee grounds are used throughout world. See statistics below
- We recycle about two 5 gallon buckets of grounds per week
- People in apartments can have a worm farm
- Any remaining or left over filters are used in a large "green" compost pile which after a year turns into a natural garden compost for winter dressing and enriches the soil
The Problem of Coffee Waste
Climate Central article
Global Coffee Statistics
- Coffee consumption has grown at the rate of 2% p.a. since 2011
- Staggering amount of coffee beans used throughout world - 144.8 million 60 kg bags of Coffee was produced in 2015 / 2016
- 152.1 million 60 kg bags of coffee was consumed in 2015
- Finland has the highest per capita coffee consumption at 12 Kg per annum. They are followed by Norway, Iceland and Denmark (2013)
That ends up as an alarming amount of coffee grounds going into our landfills!
Other Ideas for Recycling Coffee Grounds
- The latest on coffee grounds energy technology from soap to wood stain or a methane storage system
- Recycled grounds make a blooming business as a medium for growing mushrooms
- Another unique recycling idea for coffee grounds is to pave our roads as they are doing in Melbourne, Australia
- Finally, recycling of coffee "cherries" into coffee flour
In the Fall after digging in organic chicken manure I hope to have enough coffee compost to mulch heavily. The veggie garden is dormant (except for kale, greens) from October until March in our Spring. Coffee grounds are simply a valuable organic material we can recycle to improve garden soil, improve our environment, and perhaps deter some unwelcome visitors as well as enjoying fresh no-spray veggies.
Ask your favourite coffee shop if you could help them recycle some of their coffee grounds or bring home the office coffee grounds. I have not found specific scientific research on this subject but so far it does not seem to be creating any concerns in our gardens, in fact the opposite.
Spring 2016: Vegetable and flower gardens seem to be thriving using coffee grounds as a mulch and soil additive.
Links & References:
- Coffee Ground Recovery Program - Australia
- An article on coffee grounds in soils would not be complete without mentioning Vermiculture (Worm composting)
- The importance of earthworms
- Nitrogen in coffee grounds Oregon State University
- More trends, analysis & statistics on coffee than you could ever dream of
- Encyclopedia of Organic Gardening, Rodale
- John Seymour, The Self Sufficient Gardener