In a natural setting trees are fed by the rich blanket of humus on the forest floor. However, in our urban landscaped environment, fertilizer is needed to take the place of this natural food. Our urban landscape also imposes additional stresses on trees and shrubs that are not a concern in the forest setting. Stress from compacted soils, air pollution, road salts, poor drainage, and competition with turf grasses can impair the health and ultimately the growth of the tree. Without realizing it, our stressed trees are becoming more susceptible to infestation by insects and disease, further compounding the restricted grow. One of the best ways we can help our landscape plants grow healthier and make them more resistant to pest infestation is to ensure they receive a proper supply of nutrients.Deep-Root Fertilization is the most effective method to fertilize trees. This process injects water and fertilizer under high pressure 8 to 10 inches below the soil surface, where the feeder roots are. The injections are placed in a grid pattern in and around the tree’s drip line. There are many advantages to fertilizing this way. The high pressure injection forces the water fertilizer mix throughout the root zone, which not only feeds all the roots, but reduces soil compaction and encourages additional root zone aeration. Depending on your plant varieties and their health, this deep root injection fertilizer technique may be suggested at various times throughout the season, although, spring and fall are generally the best.
Even though your trees and shrubs may appear to look healthy today, call us for an analysis and our recommendations on a Deep Root Fertilization program to help keep them healthy and strong for years. Tree roots perform many functions. The primary roots grow down into the soil to provide the anchor to hold the tree upright. Secondary roots branch off and extend radially and horizontally and form the basis of the moisture and nutrient gathering system for the tree. Tertiary roots are the ephemeral absorbing roots eventually branch off into clusters of fine hair like feeder roots. It’s these feeder roots, in conjunction with natural mycorrhizial fungi in the soil that break down the nutrients found in the soil, and begin to transport them with the tree system.
While the primary and secondary roots can be found rather deep in the soil, the tertiary and feeder roots will be relatively close to the soil surface. These roots grow horizontally, to just beyond the outer drip line of the crown or foliage. This is where we concentrate applying fertilizer for the trees to benefit the most. These applications are usually timed for late fall or early spring. It’s important to remember that tree roots remain active year round and the tree will benefit from these fertilizations even though the tree appears dormant. Tree size and fertilizer analysis will dictate the actual amount of fertilizer we apply. To help prevent groundwater contamination, we don’t apply quick release fertilizers when roots aren’t active and nutrients leach out of the root zone.