Why do trees need to be fertilized?

Well, trees do not always require fertilization. If there is a specific health issue that needs to be addressed, fertilization can present a partial solution to the problem. However, it is important that any fertilization program be addressed to the actual needs of a given tree or shrub, rather than having a blanket fertilization program.

Some plants may require more fertilization, depending on established goals for a given area. If a tree is planted in a very enclosed environment, it may require more support that one that has sufficient soil mass to allow the tree to gather its own nutrition.