4. Sprinkling Coffee Grounds Around Acid-Loving Shrubs Lowers The Soil's pH
Coffee grounds are acidic, and mixing them into the soil can affect pH—slowly. But here's the catch: Fresh coffee grounds can inhibit plant growth because they tie up nitrogen in the soil as they decompose (just like banana peels), especially if large quantities are added. To lower your soil's pH without causing a nitrogen deficiency, purchase a sulfur-based soil acidifier (available at garden centers) and amend soil following the package instructions. Many popular shrubs, including azaleas, heathers, rhododendrons, and blueberries, will appreciate soil with more acidity.