A few weeks ago, I met with Paul McGuire, owner of McGuire Tree Care
Paul’s is a hands-on arborist who personally attends to each tree on his projects. He has generously shared some valuable information about tree fertilization:

Common Reasons for Feeding

Most urban gardens have very sterile soil.  The primary reason for this is the lack of organic leaf litter, which is usually raked up and blown away by gardeners to give the yard a cleaner appearance.  Also, most garden soils become compacted over time, a result from supplemental irrigation and foot traffic.

Why is Spring time a good time to Feed?

Chorotic Leaf on a Liquid Amber tree
First off, not all trees need to be fed.  Feeding is a tool used to help lethargic trees regain vigor, nurse back a damaged tree, green up the canopy of a chlorotic looking tree  (chlorotic leaf pictured), or produce stronger, more colorful flowering on ornamental trees.

Spring is an ideal time for feeding because trees can rapidly absorb nutrients during this time of year.  Also, since trees have just gone through the winter, they are using their stored reserves from the previous season to “leaf out”, which is quite taxing on older, slower growing trees.  Remember, all trees “leaf out” in spring, even your evergreen trees.  If a tree is experiencing less then expected growth, feeding can help in many cases.  Spring time feeding promotes shoot growth and leaf development, which in turn creates more opportunity for the tree to photosynthesize, creating a stronger, healthier tree.  Another added benefit from deep root feeding is the soil aeration that occurs through the injections.

What is the process of deep root feeding?

Deep root feeding is achieved using a high pressure pump, mounted on a large tank.  A locally made, water soluble granular fertilizer is poured into the tank at a certain dose, with water added.  The material is then agitated (mixed) mechanically inside the tank.  The pump is turned on, and the food is delivered from the tank, through a hose, and finally to the root tip feeder, which is plunged into the soil at a depth of 6-8″ in a grid like pattern within the trees root zone.  The food is then shot laterally into the soil at this depth, which is where the majority of the fine, feeder roots are located.  The food is quickly absorbed by the roots, and then dispersed throughout the tree.

Thanks Paul! If you have a tree that you would like Paul to evaluate for Spring feeding, please give him a call at (650) 574-0215