Coffee grounds are one of the most commonly available kitchen scraps, and gardeners often wonder whether they belong in the garden. The short answer: yes, but with some important caveats.
What Coffee Grounds Add to Soil
Used coffee grounds contain about 2% nitrogen, along with smaller amounts of potassium and phosphorus. They also add organic matter that improves soil structure over time.
The Acidity Myth
Fresh coffee grounds are acidic, but used grounds are nearly neutral. The brewing process removes most of the acid. Don’t rely on coffee grounds to acidify soil for blueberries or azaleas—they won’t change pH significantly.
Best Ways to Use Them
Add coffee grounds to your compost bin where they’ll break down with other materials. Alternatively, work small amounts directly into soil around nitrogen-loving plants like leafy greens.
Common Mistakes to Avoid
Don’t pile thick layers of grounds around plants—they can form a water-repellent crust. Mix grounds with other organic matter or spread them thinly. Avoid using them around seedlings, as the caffeine may inhibit young root growth.
The Bottom Line
Coffee grounds are a useful soil amendment when used correctly. Compost them or apply sparingly, and your garden will benefit from this free resource.
