Fall Fertilizing Tips
Written by: Jeff Wilson, Certified Arborist IL-0099A
Maintenance programs should be developed for trees and shrubs in both residential and commercial landscapes. A good maintenance program includes: monitoring and controlling insect and disease problems, making timely applications of water, mulching, and fertilizing. Tree and shrub fertilization is especially important in urban and suburban areas where soils have been altered due to construction. These urban soils tend to be heavily compacted, poorly aerated, poorly drained, and low in organic matter. Even where soils have not been affected, fertilization may be needed as part of a maintenance program to increase plant vigor or to improve growth.
Fertilizer Objectives – How and when to fertilize landscape trees and shrubs depends on:
- Maintenance objectives (stimulate new vs. maintain existing growth)
- Tree and shrub ages (generally more for younger and less for older plants)
- Plant stress levels
Determining the Need to Fertilize – Visual inspection of trees and shrubs is often a key factor to use in making fertilization decisions. Look for:
- Poor or chlorotic leaf color (pale green to yellow)
- Reduced leaf size and retention
- Premature fall coloration and leaf drop
- Reduced branch growth and retention
- Overall reduced plant growth and vigor.
In addition to observable signs of possible nutrient deficiencies on plants, soil and foliar analyses can be used to help determine or confirm whether supplemental fertilization is needed.
Application Timing
Fertilizer should be applied at various times: when plants need it, when it will be most effective, and when plants can readily take it up. In the fall, roots of established trees and shrubs take the nutrients from the fertilized soil and apply them to key health-promoting functions such as disease resistance and root development and strength. The excess nutrients are stored in the root system and are immediately available when new growth begins in the spring.
What do you need to do?
Call or email your Wachtel Tree Science Certified Arborist to have your trees and shrubs evaluated for a fall fertilization program.