Deep Root Fertilization

by Matthias Rich, ISA Certified Arborist


Iron Chlorosis is the deficiency of iron in a plant.  In most cases it is preventable and treatable.  The most common trees that show symptoms of iron deficiency are red maples, pin oaks, and river birch trees in suburban areas.

Eventually, the iron that is in the ground gets used up, and slowly the tree runs low on this micronutrient.  Our Indiana soil pH is a little higher than what most plants prefer.  Most plants do best when the soil pH is 6.5, but here in Indiana, our pH will range from 7-8.


There are three common methods to treat this ailment.  First, you can inject your tree with iron products, which work the fastest.  You will see a change in your tree within a week or two, but it only lasts 6-8 weeks.  I would recommend this method if there is an important event going to happen in the middle of the summer. 

The second method is by deep root feeding your tree with fertilizers.  The “deep root” means that we will insert a probe under the grass root line so it is directly implemented to the tree’s roots.  Granular applications don’t work well because grass roots will suck everything up before tree roots get to the nutrients.  This method is typically done in spring and fall because there is more rainfall to disperse the nutrients around in the ground. Usually the tree will benefit from these fertilizers for about 6 months.

Finally, the last method is to address the problem and that is lowering the pH of the soil.  This method typically lasts 2 years when done correctly.  But since the rain will have a higher pH than the new adjusted soil, it will slowly fade away.  Results can be seen in about a month, and will last for the longest period of time. 

Consider maintaining your tree on one of these programs to get the end results you want.  It takes years for a tree to decline from iron deficiency, and it will take years for it to be a perfect green again.

Image Credit: Cover, photo by Becker Landscape; Body, photo by Becker Landscape.

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