An often utilized commercial fertilization process for trees and shrubs is to inject liquid fertilizers into the roots. An elongated probe injects water-soluble plant food cartridges that deliver nutrients and water directly into the tree root area. The tip of the injection needle is entered four to twelve inches into the soil at two- to three-foot intervals.
Placement of Fertilizer
Fertilizer should not be concentrated around the base or trunk of a tree or shrub, but should be applied over as much of the plant's root zone as possible. For trees and shrubs, fertilizer should be applied over an area twice as large as the crown spread.
Factors Affecting Fertilizer Uptake
Numerous elements impact how easily, and how well, trees and shrubs assimilate fertilizers. The most significant uptake factors are:
- Fertilizer variant - fluid forms are assimilated faster than organic, slow-release, or dry forms
- Soil type - clay particles and organic matter intake more nutrients than sand, so fertilizer needs to be applied more frequently in sandy soils, but with lesser rates each time due to leaching potential
- Soil moisture content and soil temperature - nutrient uptake is faster in moist warm soils
- Plant vigor - plants under stress will take in less available nutrients because of damaged or decreased root systems
Fertilizer should be utilized when plants require it and can readily accept it. Late summertime and early autumn fertilization may hasten new growth that is not winter hardy, and summer drought could interfere with nutritive uptake. Spring, fall, and winter applications are satisfactory. A split application might be beneficial, applying half the annual rate in early spring and the balance in the fall as or after plants go dormant. If water is unavailable, don't fertilize altogether - plants will be unable to assimilate the nutrients.
*Tree and shrub fertilization is only one ingredient of total plant maintenance. Fertilization may not assist a plant if it is under stress from poor soil aeration or drainage, saturated soil, inadequate light or space, or excessive pest problems. All factors influencing plant growth should be kept at optimal levels to ensure plant vigor. Call Paramount to speak to a professional about the best way to fertilize your trees and shrubs. (513) 984-5200*