If you are a big coffee drinker and are just getting into composting, use your grounds as a fantastic, free, natural fertilizer. (And if you ever have cold, leftover coffee in the pot, go ahead and pour that directly onto your garden or lawn, too.) You’re right that grounds can be a teensy bit acidic (though used grounds are far less acidic than raw grounds), so they’re great for clay-based alkaline soils.
Or sprinkle the grounds over acid-loving plants (which like a low pH of around 4 or 5) like azaleas, rhododendrons, potatoes, and blueberries. If your soil is on the more acidic side, and you’re not interested in growing any acid-loving plants, just temper the acidity of your grounds by throwing them in the compost heap instead of directly on your garden.
And guess what else? Coffee grounds are… wait for it… a natural slug repellent, so they’re a rich fertilizer and effective pesticide in one. Without all the chemicals.
For those out there who don’t drink coffee, but want to fertilize naturally and save money: Ask the barista at your local coffee shop for some leftover grounds. Or maybe you work with a bunch of caffeine junkies? Collect grounds from the kitchen at work and bring them home.
Story by Tobin Hack. This article originally appeared in Plenty in April 2008.