If your breakfast includes bananas and a cup of joe, you'll have enough nutritional scraps to feed your roses (Rosa spp.) too. Banana fruits and peels, composted first or not, add phosphorus and potassium to rose soil, and coffee grounds provide pinches of nitrogen, calcium and magnesium.
Vibrant, healthy rose bushes fight off diseases and produce the best blossoms, so a gardener does what she can to make her roses strong. You give your roses some of the ingredients for healthy living, like sunlight and air, by selecting a good planting site. Mother nature provides both water and nutrients, but just as you add irrigation when needed, you can supplement nutrients by adding fertilizer to the soil. Consider both coffee grounds and banana peels in that category.
When you add compost or fertilizer, you feed the soil, not the rose plant growing in it. Plants produce their own food, taking up nutrients in the soil and converting them into sugars by the magic of photosynthesis. When you add material to the soil, you replace the nutrients your roses have used, providing them with a steady supply. This should be done every month or so throughout the growing season. The three primary nutrients required for rose growth and health are nitrogen, potassium and phosphorus. Between coffee grounds and bananas, you'll add all three to the soil.
Coffee Grounds for Nitrogen
Coffee grounds are 2 percent nitrogen, so from the get-go they increase the nitrogen level of the soil. According to the Oregon State University Extension service, they are an excellent source of nitrogen for composting. Keep the grounds to 25 percent or less of the pile. Rose gardeners can also spread several inches of coffee grounds directly on the rose bed soil. Either work the grounds into the soil or else cover a thin layer with several inches of dried leaves to prevent them from drying out.
Banana fruit and peels are rich in phosphorus and the peels in potassium as well. Roses need potassium for vigor and phosphorus to bloom, so bananas and roses are a match made in plant heaven. Some gardeners prefer to chop up bananas and compost them in the bin but other simply bury fruit or peels at the base of the plants. If you add uncomposted organic material directly to the soil, it's a good idea to toss in a few tablespoons of nitrogen fertilizer at the same time, since it takes nitrogen to break down the material.