Mangoes are a tropical fruit that ripen in the summer. Most varieties of this tree grow large and make attractive shade trees with their year-round foliage. Although they grow like weeds in some tropical areas, such as Kona, Hawaii, you can help a mango tree remain healthy and produce the maximum amount of fruit by fertilizing it correctly, using either an organic plant food or chemicals.
When it is available, composted cow manure helps mango trees to put out healthy new growth and produce the flowers that turn into fruit. The Online Information Service for Non-Chemical Pest Management in the Tropics recommends spreading about 20 lbs. of composted cattle manure around the drip line of mature trees two weeks before you give them chemical fertilizer or before and after your rainy season.
Organic compost works to provide mango trees with the nitrogen, phosphorus and potassium they need to grow big and strong and produce plenty of fruit. With compost, you create a continuous source of nutrition for your tree by spreading a 3- to 4-inch ring of it around the tree's drip line. Every time rains occur or you irrigate your tree, the nutrients from the compost leach into the soil. Reapply compost twice each year.
During its first three years of life, the Online Information Service for Non-Chemical Pest Management in the Tropics recommends using an ammonium sulfate-based fertilizer on your mango tree, four times each year, at evenly spaced intervals. After the tree is older than three years, it says to fertilize it with 1 lb. 4 oz. (600g) of nitrogen, phosphorus and potassium four times each year, divided into equal doses.
The California Rare Fruit Growers suggest giving mango trees chelated mirconutrients, especially iron, three to four times each year until midsummer.
Organic fertilizers, such as fish emulsion, are favored by many growers and are recommended by the California Rare Fruit Growers. Mango trees can suffer from burns that chemical fertilizers cause, it says, adding that when mangoes grow in sandy soil they need more fertilizer than trees that grow in loamy or clay soil.