In general, banana plants need a fertilizer with high amounts of potassium (K), along with nitrogen (N) and phosphorus (P). Soils vary around the Islands, some being richer than others. The University of Hawai`i recommends applying 2 lbs., three times a year of a fertilizer similar to 10-5-20 (N-P-K). This amount is applied per mat. When referring to bananas, a group of plants is known as a mat. A properly maintained mat will have one plant in fruit, one plant half-grown and one plant just emerging from the soil.
Applying compost to the surface of the banana mat is beneficial, but most likely will not supply enough nutrients, especially nitrogen, for optimum growth.
