Add some compost to the soil around your mango tree, along with some wood ash, which contains potassium to encourage the fruit to grow and enhance the fruit's flavor.
Spread a 1-inch layer of mulch around the base of your mango tree, especially if it is growing in a container. Mulch will help insulate the soil.
Refrain from over-watering your mango tree or it could die. In fact, the soil should go from wet to dry to wet. It does not have to stay moist at all times, like other trees.
Try to water your mango tree in the morning or early afternoon. Water that sits on the leaves overnight can become a breeding ground for fungus.
Find a spot where your container-housed mango tree can get the most direct sunlight during the day – then leave it there. Moving the container around to new locations could cause sunburn and/or the leaves to drop. While some dropping is natural, it takes weeks if not months for a mango tree to adapt to new lighting conditions.
Swivel your container-housed mango tree 180 degrees about once a week so that all sides receive direct sunlight and so that branches on one side of the tree don’t over-arch toward the sun.
Fertilize your mango tree in the spring and summer, using 1 tablespoon of 12-5-9 fertilizer mixed with one gallon of warm water for the tree’s first three years. After that, use a 4-4-8 mixture. These numbers – called the fertilizer’s grade -- refer to the amount of nitrogen, phosphorus and potassium, respectively, that the fertilizer contains. The potassium should always remain high, as it will help the tree to flower.
Spray your mango tree with copper sulfate once a week if you see black dots on the fruits or leaves, or if the growing tips die by curling and turning black. Known as anthracnose, this fungal disease can spoil the fruit. Spray the copper sulfate on the leaves only, blocking the soil with rags.