Used coffee grounds offer many benefits to plants, flowers, and vegetables—improving water retention, drainage, and soil aeration are at the top of that list. Coffee grounds also allow certain beneficial microorganisms to thrive and attract earthworms, which are a garden’s best friend.
Because coffee is acidic, many people believe that adding grounds to your garden will increase the pH level of your soil, but this is a myth—only fresh coffee is acidic. Once it’s been used, most of the acidity ends up in your cup. The grounds are pH neutral, clocking in at about 6.5.
While used coffee grounds won’t alter the pH level of your soil, they do enrich it in other ways. Grounds are about 1.45% nitrogen and contain trace minerals, including magnesium, potassium, phosphorous, and calcium, which are released as they break down. This is good news for plants that do well in nitrogen-rich soil, such as spinach, corn, blueberries, roses, rhododendrons, and azaleas. Tomatoes thrive on nitrogen and particularly enjoy coffee grounds.
Source: House Method
Visual by ecogreenlove
via Use your Coffee Grounds in the Garden [Infographic] — ecogreenlove