After you’ve enjoyed a fresh banana, what do you do with the peel? You can add it to your compost bin or boil it to make banana-peel tea, but why not try banana-peel fertilizer spray? Bananas are loaded with nutrients like calcium, potassium, phosphorous and sulfur, which plants love. To make it, dry the peels in a hot, sunny place until they are completely dry and brittle. Pulverize the peel in a blender or food processor, and add the powder to a spray bottle with water. Spray it at the base of your plants to give them an all-natural boost.