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Recycle your coffee grounds

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Recycling your coffee grounds gives you the opportunity to diminish landfill waste and lavish your plants and vegetables with an effective, nutrient-filled compost for your garden.

How to recycle your coffee grounds

Coffee grounds are rich with minerals and vitamins, containing nitrogen, phosphorus, potassium, and a desirable, slightly acidic pH level between 3.0 and 5.0. Consult a gardening specialist if you are unsure how the grounds will react with certain plants. Otherwise, consider these tips to turn your spent grounds into a powerful homemade fertilizer:

  • Collect the grounds: Keep an old coffee can or other container beside your kitchen sink to avoid the temptation of dumping coffee grounds down the drain or in the trash. Spent grounds should be used in a relatively short time and kept dry, as they tend to mold.
  • Apply coffee grounds directly to your plants: Before watering your outdoor plants, layer your soil or target garden areas with coffee grounds. Plants such as azaleas, rhododendrons, ferns, roses, gardenias, blueberries, cranberries, oaks, and spruces respond well to coffee-ground mulch. You can also sprinkle the grounds directly on the soil of potted houseplants.
  • Make a garden compost: Add coffee grounds (along with used, non-chlorine bleached coffee filters to your compost bin to neutralize pH levels and quicken the decompositioning process. The grounds should account for no more than 25 percent of the composting matter and a teaspoon of lime or wood for each 5 pounds of grounds can be added to balance out acidity levels.[1]
  • Make a liquid fertilizer: Diluting coffee grounds with water creates an excellent liquid fertilizer. Mixing one half pound can of coffee grounds into a 5-gallon container of water is recommended.
  • Use coffee grounds as a natural pest deterrent: Surround plants sensitive to pests, especially worms, with a mixture of coffee grounds and eggshells. This acts as a natural repellent and keeps worms well fed and happy without having to resort to chemical pesticides.
  • Seek outside help: If you don't brew coffee at home, visit a local coffee house and ask for their spent coffee grounds. Starbucks is active in contributing grounds to customers for gardening use through its Grounds For Your Garden program.

Find it! Recycled coffee ground products

Although coffee grounds are most often recycled for gardening purposes, your fireplace can benefit as well. Fireplace logs made from used coffee grounds emit less carbon dioxide than manufactured logs while reducing landfill waste.

Recycling your coffee grounds helps you go green because...

  • It reduces waste that would otherwise end up in a landfill.
  • It gives back to the earth while lessening your reliance on chemical pesticides and fertilizers.

Given that millions of people drink coffee on a daily basis—approximately 56 percent of the American adult population—millions of pounds of coffee grounds are discarded.[2] At a typical Starbucks store, coffee grounds account for 40 percent of trash by weight.[3] In 2005, 28.5 million tons of food waste, including coffee grounds, were discarded in the United States alone.[4]

Used coffee grounds, however, don't have to end up in the landfill. They can be used as a natural, chemical-free fertilizer and pest control agent for your garden or houseplants. Commonly used chemical gardening products, such as fertilizers and pesticides, can reduce soil efficiency and impede a plant's ability to naturally ward off harmful insects and diseases. Groundwater is also at risk of contamination from chemical gardening treatments: studies report that surface water in 100 percent of all large streams and rivers tested positive for pesticides.[5]

As a pest control agent, it has been found that slugs and snails (common garden pests in cooler climates) don't like caffeine. Studies show that using a spray solution with high levels of caffeine, such as 1 or 2 percent, kills off 60 percent and 95 percent of slugs, respectively.[6] Coffee grounds aren't likely to kill garden mollusks because they contain less caffeine (instant coffee contains approximately .05 percent caffeine while drip coffee has about twice that amount). However, applying coffee grounds around plants can act as a mild, but effective deterrent. As such, coffee grounds are considered a safe alternative to metaldehyde.

Glossary

  • metaldehyde: A chemical pesticide used to poison slugs and snails that is toxic when ingested by other organisms. including humans.
  • mulch: Matter—comprised of a variety of organic (leaves, bark, paper, compost, or manure) or non-organic materials (such as gravel)—placed on top of the soil to control erosion and moisture levels and discourage weed growth.

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