Coffee Grounds! The Free Garden Secret

Many people don’t know this, but all those coffee grounds from Starbucks are provided to gardeners free for the asking. Most Starbucks stores have a bucket where they place the garden grounds somewhere in the store. If not or if the bucket is empty they are generally more than happy to fill up some bags for anyone who asks. Starbucks discusses their garden grounds program at http://www.starbucks.com/aboutus/compost.asp and gives information and tips on using the grounds in the garden.

Starbucks reports that most of the acidity is removed in the brewing process, leaving used grounds with an average PH of 6.9 and a carbon-nitrogen ration of 20-1. Starbucks commissioned a study in 1995 conducted by the University of Washington College of Forest Resources to better understand the make up of organic matter in coffee grounds and found the following:





Primary Nutrients
Secondary Nutrients




Nitrogen 1.45%
Phosphorus ND ug/g
Potassium 1204 ug/g Calcium 389 ug/g
Magnesium 448 ug/g
Sulfur high ug/g
Notes:




ND = indicates sample is below detection limit
ug/g = microgram / gram








Coffee Grounds Are One Of The Best Kept Garden Secrets And Offer The Following Benefits:
• They smell great!
• They are a source of nitrogen that is widely available year round in all parts of the country.
• They are easily stored for days in a closed plastic bag. But are best used within two weeks.
• Coffee-ground mulch can help reduce the ravages of slugs and snails if placed around the perimeter of the garden.
• They are a great food for worm farming. Worms love coffee grounds and turn them into great castings for the garden. Make sure to feed them with other items and place them in a corner of the bin rather than spreading them. The worms will find them in the corner and process them at their own pace.
• Particularly where the soil is very alkaline and/or very dense clay coffee grounds do wonders as a soil amendment because they can lower the soil pH over time.
• They are available in large quantities for free from Starbucks!
Use Coffee Grounds In The Following Garden Applications:
• For a great source of slow-release nitrogen, dig coffee grounds into the soil around plants and water in well. They are particularly great for mulching acid loving plants like rhododendrons and azalea. A rate of 10 pounds (dry weight) per 1000 square feet would be conservative and not have a drastic impact on soil pH.
• Coffee grounds are a great accelerator for compost to increase nitrogen balance. Consider coffee grounds "green" material similar to grass clipping. One of the great things about composting coffee grounds is that the microbes that do the composting will turn the coffee from acidic to a neutral pH. So coffee grounds do not make compost acidic. The Environmental Protection Agency suggests adding no more than 25 percent volume coffee grounds. Adding this 25% to fall leaves or other brown matter will make great compost in a minimum of time. An added benefit is that grounds absorb and hold moisture which is critical to the compost pile.
• Make Coffee tea from grounds for a gentle, fast-acting liquid fertilizer. Use about a half-pound of wet grounds in a five-gallon bucket of water. Place the grounds in an old pair of panty hose or sock and let the bucket sit covered for about two weeks before using. This tea can be used when watering or better yet, as a foliar spray.
• Some people mix grounds into soil for houseplants, but it may be better to avoid using coffee grounds directly with potted houseplants, not only because of the potential for fungal growth but also potential buildup of soluble salts. A better approach is to compost the grounds first with the addition of brown matter for a few weeks and then use the compost as a dressing or soil additive for house plants.
• Encircle the base of the plant with a coffee and eggshell barrier to repel pests.
With the number of Starbucks stores increasing all the time it is not hard to find one or more on the way to work and stop in each day, not only for a great cup of coffee, but for a bunch of free grounds that will do miracles in the garden.

John Berends is a free-lance writer and an owner of Greenhouse and Garden Supply. John can be contacted at john.berends@greenhouseandgardensupply.com and you can visit his website at http://greenhouseandgardensupply.com.