What Is Deep Root Fertilization?



Wondering what deep root fertilization is and how it works? Have you read conflicting views about this process? Despite the mixed feedback available on the internet, most qualified arborists agree that this is a highly beneficial investment for the health and longevity of your trees. Petalon’s trusted team works with a local network of ISA-certified arborists who are in favor of deep root fertilization.

Although many of the trees and shrubs on your commercial property may look similar to those in forested areas, they need regular care and attention to survive in an urban environment. Whether it is because of transplantation, incompatibility to the native area, or pollution, even the established trees on your property are vulnerable to tree pests, diseases and nutrient deficiencies.

  • The basics of deep root fertilization. Tree roots thrive in healthy soil that is nutrient-balanced and rich in oxygen. Deep root fertilization addresses these aspects. The process involves injecting liquid fertilizer into the root zone of trees and shrubs. A skilled arborist uses special equipment to release the liquid materials under controlled pressure. This is how it improves the robustness of your trees:
  • The liquid fertilizer activates the microbial activity that enriches the soil and increases its nutrient levels.
  • The pressure-controlled release aerates the soil, giving it a much-needed oxygen boost.

Essentially, it is like a deep conditioning treatment which allows you to deliver nutrients to your plants and trees in the fastest possible way.

  • Why should you consider deep root fertilization? Has a soil sample analysis revealed a deficiency in nitrogen (N), phosphorus (P) or potassium (K) levels? These nutrients are essential for the healthy growth of the trees and shrubs on your property. Do your plants or trees seem vulnerable to pests? Have you noticed yellowing or off-color leaves, or new shoot growth that lacks vigor? No matter why your trees are struggling, deep root fertilization will help nourish them back to good health, quickly and efficiently.
  • What are the steps involved in deep root fertilization? First, a qualified arborist will study the soil sample and blend a fertilizer to bring the soil’s NPK (nitrogen, phosphorous, potassium) levels at par with the requirements of your trees and shrubs. The next step is to use special tree injection equipment to place the liquid fertilizer 6 to 8 inches beneath the soil’s surface. Typically, arborists will inject the fertilizer 2 to 3 feet apart in a grid pattern, covering the area under each tree’s canopy and slightly beyond.
  • What is the ideal time for deep root fertilization? Most arborists recommend deep root fertilization once or twice a year, in the spring and/or fall. Springtime provides a nutrient boost for the growing season ahead and fall is ideal for the trees to store nutrients that help them through their winter dormancy.

Remember, deep root fertilization may not be suitable for every tree, especially certain diseased or stressed trees, or newly planted ones that need time to establish their roots. This process is not beneficial during the summer and winter months. However, when you need deep root fertilization for your trees, rely on a professional arbor care company, such as earth landscape. We have the necessary skills, experience and equipment to make commercial arbor care easy, safe and affordable.