Coffee grounds, both used and fresh, offer an excellent natural direct fertilizer or addition to the compost pile. Coffee grounds offer a fertilizer value of 2.0-0.3-0.2 and also contains a small amount of both calcium and magnesium, according to the Purdue University. Adding coffee grounds to the compost pile helps add nitrogen.
Sprinkling coffee grounds around plants works as a low-level fertilizer. Apply prior to a rain shower or water the coffee grounds into the soil prior to application. Used coffee grounds are less acidic than fresh in composition.
The acidic nature of coffee grounds makes them ideal for application around acid-loving plants such as azaleas, blueberries or rhododendrons. Adding coffee grounds to the soil around bigleaf hydrangeas will help ensure that the blossoms appear blue. To render the garden soil slightly acidic over a large area, it is suggested by Purdue University that 10 pounds of dry coffee grounds be worked into the soil for every 1,000 square feet of garden space.
Add no more than 25 percent coffee grounds to any compost pile. Layering the coffee grounds into the compost pile works best. Add a layer of grounds, a layer of leaves and a layer of grass clippings. Be sure to mix the bin up every week. To render the compost more alkaline, add ground up egg shells. Moldy coffee grounds also work well in a compost pile.
Coffee grounds encourage earthworms to frequent the garden because the worms enjoy consuming the coffee grounds. Professional earthworm farmers use coffee grounds as a source of food for their worms on a regular basis.
Mixing coffee grounds into the garden soil at the time of planting acidic soil-loving plants works in a similar way to adding peat moss. Mix the coffee grounds into the soil at a ratio of 25 percent coffee grounds with 75 percent garden soil when planting.