Why fertilize a tree?
If you fertilized your lawn, you may not have fertilized your trees. Tree care companies have specialized equipment that can deliver fertilizer right where the trees need it – the tree’s root zone, just below your lawn’s root zone. In forests, trees shade out grass and other plants so the tree’s roots don’t have to compete with roots of other plants. Trees are free to absorb all the nutrients they need. Your lawn is a harsher environment for trees. In your lawn, trees must compete with grass roots for valuable nutrients. When you drop fertilizer on top of your lawn, the grass receives most of the benefits. A different type and method of fertilization is used to fertilize trees than what is used to fertilize lawns, since trees don’t grow the same as grass. For trees, slow release fertilizer is applied directly to the tree roots, just below the grass roots. This can be done with special liquid fertilizers injected into the soil (sometimes called “deep-root fertilization”) or dry fertilizers poured into holes drilled into the root zone of the tree. Trees also respond to fertilizer differently than your grass. Over-fertilization can create tree health problems, so the need for fertilization should be determined by measuring annual growth, checking visual symptoms and/or chemically analyzing the soil or tree leaves. Tree fertilization should be done according to ANSI A300 Part 2 standards for tree fertilization.
Deep root fertilization is a process where a high quality nutrient solution is injected into the root zone of trees. The materials are injected into the root zone under pressure which helps aerate or provide much needed oxygen to the root system. The soil injection begins just below the surface and goes to a depth of 12 – 14 inches. Soil injection sites are placed about 2 or 3 feet apart in a grid pattern throughout the canopy area and beyond the drip line. (See the diagram below.)
Normally, fertilization programs should be repeated once or twice a year. There will be instances where severe root damage has occurred, soil compaction exists, or other health problems are present. In these instances it may be recommended to increase the frequency in order to improve conditions in and around the root zone which can improve overall health and vigor.
Roots are opportunistic and develop where ever oxygen, nutrients and moisture are present. Ongoing deep root fertilization programs improve the oxygen content, microbial activity, and nutrient levels within the soil, leading to improved environmental conditions around and within the root zone.
There will be times when we will recommend amendments to the standard mixture when certain nutrient deficiencies or health concerns are present.