Fertilizing the trees & shrubs in your yard
The warm weather in the High Country of Colorado makes for a good time to fertilize the trees and shrubs in your yard. A popular misconception about fertilizing is that the more you apply the more the plant will grow. According to Erv Evans, a consumer horticulturist with North Carolina State University, fertilizer is not plant food. “Plants use water, carbon dioxide, elements from fertilizer, and energy from the sun to produce their own food,” says Evans. Evans also adds that “synthetic and natural fertilizers provide nutrients for plant growth.”Applying the correct amount of fertilizer promotes flower and foliage production while too much fertilizer can lead to a decline in the health, or even death of a plant. Poor growth in a plant, such as light green or yellow leaves, leaves with dead spots, leaves smaller than normal, fewer leaves or flowers than normal, short annual twig growth, dying back of branches at the tips, and wilting of foliage, do not always mean the plant need to be fertilized. Although fertilizing may help, the cause of the poor growth needs to be remedied in order for a plant to remain in good health.The cause of poor growth can be attributed to things like poor soil aeration, moisture and nutrients – either not enough or too much, weather conditions, the wrong pH for the soil, or a disease. Transplanted trees and shrubs will take a while to get back to their normal growth habits. Construction in the area can also damage plants and cause them to go into shock. Remember, applying fertilizer will not fix what is going on with the plant. Try your best to determine the cause of a problem the plant is experiencing and remedy the problem before fertilizing. Nitrogen, phosphorus and potassium are nutrients plants need to grow properly, and generally a fertilizer has these nutrients in a ratio of three parts nitrogen, one part phosphorus, and one part potassium.The most common ways to apply fertilizer to trees and shrubs are foliar: spraying fertilizer on the foliage, granular: spreading the fertilizer on the ground underneath the plant, and applying the fertilizer below the soil surface. Foliar fertilizing does not last very long, and care should be used not to burn the leaves by using too much or using a fertilizer which is too strong. Applying granular fertilizer to the soil is most effective in a bed without grass or ground cover underneath the canopy of the tree. Applying the fertilizer below the ground, also known as deep root fertilizing, is more work than the methods mentioned above; however, this method produces the best results. Consult your local garden center to find the correct fertilizer to use and to determine the most effective application method. This article was written by Peter Alexander of Neils Lunceford Landscape Design/Build (www.neilslunceford.com) with help from “A Gardener’s Guide to Fertilizing Trees and Shrubs” by Erv Evans, and the Colorado University Extension website on Fertilizing Trees and Shrubs. Peter can be reached at (970) 468-0340, or at firstname.lastname@example.org
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