Tree fertilization is an important aspect of tree care. Like most living things, trees and shrubs require essential elements to grow. These elements are typically taken in through the plant's root system, which means that they are dependent on the soil surrounding them. Many landscape trees can be growing in soils that do not contain sufficient nutrients for satisfactory growth and development. In these situations, it may be necessary to fertilize to improve plant vigor.
Fertilization must be applied correctly or it may adversely affect the tree in a negative way. It is important to understand what nutrients are available in the surrounding soil and only supplementing those elements as needed. Too much fertilization is not a good thing. Soil conditions, especially pH and organic matter content can vary greatly, making the proper selection and use of fertilizer a complex process.
Fertilizing a tree can improve growth; however, if fertilizer is not applied wisely, it may not benefit the tree at all and may even adversely affect the tree. Mature trees making satisfactory growth may not require fertilization. When considering supplemental fertilizer, it is important to know which nutrients are needed and when and how they should be applied.
Mulching around your landscape trees, especially if the tree is a specimen-type tree surrounded by lawn, can be very beneficial if done properly.
Mulching can reduce a number of environmental stresses by providing a stable root environment that is cooler and contains more moisture than the surrounding soil during the heat of summer. Mulch also helps reduce the competition from the surrounding turfgrass that can deplete the soil of certain nutrients and moisture. Mulch can also prevent mechanical damage by keeping machines such as lawn mowers and string trimmers away from the tree's base.
It is vitally important that mulch be applied correctly. Too much mulch can block water from penetrating the soil. Mulch should be about 2" - 4" deep and cover the entire root system. Care should be taken to not cover the actual trunk of the tree. At the base of the tree there should be a mulch-free zone of about 1" - 2" wide to prevent trunk decay.