Trees growing in urban areas typically require more attention to fertilization
(nutrient management) than do trees growing in a more natural habitat. Urban sites can be lower in fertility because of topsoil removal, compaction, paved areas and increased landscape competition. Urban shade trees need more fertilization attention. The overall objectives in a fertilization program should be:
- Accelerate root growth of newly planted shade trees. This helps in initial landscape establishment. Do not use root stimulators. Avoid nitrogren applications initially. Shoot growth will be accelerated at the expense of root growth.
- Fertilize to maintain the existing growth, health and vigor of mature trees. Mature shade trees may not need fertilization on a regular basis. This depends on the site (competition present) and results of soil analysis.
- Rescue or partial recovery of declining trees can be accomplished with fertilization and cultural practices.
- Fertilize to current nutrient deficiencies.