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About Fertilizer And Fertilizing Evergreen Trees

Knowing the best way to apply fertilizer to your evergreen trees requires some basic knowledge about the product you are using. Fertilizers, whether organic or chemical, are always labeled with three numbers. For example, a bag of fertilizer may have the numbers 12-12-12 or 28-8-3 or 0-0-64 on the label. These numbers hold the key to proper fertilization selection.

The numbers stand for N-P-K. The “N” refers to Nitrogen. “P” is Phosphorous. “K” is Potassium. Each is listed on fertilizer labels because each plays an important role in the development of the tree.

• Nitrogen is the first of the three numbers on the label, and it is the nutrient needed to make the tree a dark, lush green color.
• Phosphorous is the second number, and it helps the growth of strong, deep roots.
• Potassium is the third number, and it gives the tree structure endurance for extreme weather conditions.

The numbers represent the percentage of chemical weight to inert matter. For example, if you have a 10 pound bag of 20-10-10 fertilizer, then two pounds of the product is Nitrogen, one pound is Phosphorous, and one pound is Potassium.

Once the numbers make sense, then it is necessary to find the right product for the project. If you are looking for a basic fertilizer that serves all the functions, a 12-12-12 mix is good. If you are seeking a dark green look, then a higher first number with lower second and third numbers is the choice. For a newly planted tree, the middle number should be higher to help the root development.

Some basic timing is important, also. Fertilizers with high nitrogen levels, or 1st numbers, are best applied in the cooler parts of the growing season, early-mid spring and mid-late autumn. If you apply these during the heat of the summer, the chemicals will stress out the tree. On the other hand, fertilizers with a high third number are good for late spring and late fall to assist the tree through the weather extremes.

The final consideration is the type of product and applicator to use. As a general rule of thumb, fertilizers are most effective in granular form. The granules fall to the surface and connect with the soil where the proper chemical reaction can take place. The use of liquid fertilizer on a small scale is virtually worthless. It does not produce the same desired effect because the chemicals do not carry as high of a weight concentration. It takes a much greater volume of liquid fertilizer to gain the same effect as granular fertilizer.

In the same vein, using “weed and feed” products for post-emergent weed control is also not the most effective method. The product you are applying needs to both reach the soil to provide the nutrients, and stick to the leaves of the weeds to kill them. It is impossible to get 100% coverage in both of these areas at the same time with one product. Instead, fertilize the tree first with a basic granular fertilizer, and then spray the area or around the tree with a post-emergent weed control.

The applicator can be a broadcast spreader or a drop spreader, both are equally effective. It is very important, however, to have a product that has a spreader setting listed on its label that corresponds with your spreader. Many turf fertilizer brands offer both the spreader and the fertilizer products. This eliminates the guess work that can come from having a spreader and fertilizer that come from competing companies. Competing companies do not always list the proper settings for their competitors’ products.

Again, a basic knowledge about the numbers and what they accomplish, coupled with a proper fertilizer and spreader combination will make the task of successful tree fertilization very doable for virtually anyone.