quote: Banana tree Fertilization: Their rapid growth rate make bananas plants heavy feeders. During warm weather, apply a balanced fertilizer once a month--a 8:10:8 NPK fertilizer appears to be adequate. A mature plant may require as much as 1-1/2 to 2 pounds of the above fertilizer each month. Young banana plants need a quarter to a third as much. Spread the fertilizer evenly around the plant in a circle extending 4 feet from the trunk. Feed container banana plants on the same monthly schedule using about half the rate for outside plants.