Papayas are fast growing plants which require an abundant supply of nutrients if they are to be highly productive. Fertilize the plants monthly using a 4-6-8- or 10-10-10 mixture.

Frequent applications of small amounts of fertilizer are best for continuous papaya growth and fruit production. Young plants should be fertilized every 14 days with 1/4 lb of a complete fertilizer with the amounts increasing as trees become larger. Complete fertilizers include nitrogen (N), phosphate (P₂O₅), potash (K₂O), and a source of magnesium (Mg).

Additional Resource
http://edis.ifas.ufl.edu/MG054