If I add eggshells and coffee to my roses, do I have to bury them, or will the soil receive the nutrients? I usually add eggshells, used ground coffee, and banana peels to my flowering garden - mostly my hydrangeas and roses. Is it a "must" that they are buried, or is the top of the soil suitable? I bury the bananas but usually crush the eggshells, toss, and slightly scatter over soil. The ground coffee is usually sprinkled. I drink a cup a day in a Keurig so I put very little, daily.