But it turns out that coffee grounds contain a good amount of the essential nutrient nitrogen as well as some potassium and phosphorus, plus other micronutrients. So in general, when added to a garden, coffee grounds can nourish and fertilize the soil (and the plants growing in it) with those elements and minerals. Dry Out Banana Peels Break Them Apart And Bury Them Around Your Roses To Make Them Bloom Like Crazy Photo Credit Mug Garden Lawn And Garden Planting Flowers When you switch to instant coffee, you’re looking more at about 50 to 70 milligrams of potassium per serving. Potassium in coffee grounds . First thing to consider is the nutritional content of coffee. Deters slugs when sprinkled in a ring around the plants. Thus you can add coffee grounds directly to the compost as use it as fertilizer for your rose. Contains potassium, phosphorus & nitrogen plus small amounts of copper, magnesium and calcium. Each of these elements has their impact on the soil, and the...