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Fall Fertilization - Pay attention to roots

Updated: Apr 19, 2022

When it comes to taking care of trees, people tend to give the majority of their attention to the parts of the tree growing above ground, ignoring what is growing below the surface.  It is often easy to spot when a tree has broken branches, large wounds, or hazardous pieces of dead wood, but the root systems of trees are most often overlooked and ignored. These systems are essential for the long term health and viability of a tree.  Often times we don’t realize that a tree’s root system can be quite extensive, often containing up to 20-40% of a tree's entire biomass. Most roots are found in the top 18 inches of the soil, and 50% of those are found in the top 6.  This is the area with the most nutrients, water, and oxygen, which are the essential ingredients that roots need to thrive.

Roots often face several challenges in our urban environments.  Poor, disturbed, and compacted soils are common, and urban soils may be depleted of nutrients. Prolonged periods of dryness can reduce the readily available moisture, but excessive moisture and poor drainage can reduce the availability of oxygen, leading to root decay.  Soil fill and too much mulch around the base of a tree can also damage roots by essentially suffocating the root system, which can lead to stem girdling roots. With all of these prospective problems it’s easy to see why urban trees don’t live as long as forest trees.  

In the fall, while the parts of the tree that grow above ground start to slow down, the root systems remain active.  This makes fall a very good time to perform fertilization and root system treatments, among other procedures.  Our fall fertilization blend is a water-soluble micronutrient treatment that includes beneficial rhizosphere (root zone) bacteria and 3-0-20 nitrogen/phosphorus/potassium fertilizer.

Fertilization helps aid in a plant’s recovery from stress, reverses mineral deficiencies that cause chlorosis and necrosis, and improves root function without stimulating excessive top growth. This all happens while providing soluble nutrients in acidic, neutral, and alkaline soils.  When more vegetative growth is desired we will mix in a higher nitrogen fertilizer as well. Fall fertilization treatments prepare plants for the cold weather, damaging wind, lack of moisture, and frozen ground.

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