What is the best type of fertilizer for most types of trees
St. Clair County Michigan
Fertilization of trees is usually done only if there is a deficiency of one or more nutrients required for the tree to thrive. The pH of the soil can also influence whether your trees are taking up the nutrients they require.
Most soils contain the nutrients needed. Applying fertilizer to the soil when it is not required does not benefit the tree and it is costly for you. Note that trees make their own food from the nutrients in the soil through the process of photosynthesis
In order to determine if your soil has all of the nutrients needed and what the pH (acidic or basic) is, you should have your soil tested. Trees have preferences as far as soil type, soil acidity, sun, shade and moisture conditions. Some can withstand variations of their preferred growing conditions while others will exhibit signs of stress and not thrive. For example red maple, Acer rubrum, cannot take up all of the nutrients it requires from soil that has a high pH and will show chlorosis in the leaves. This is where the vein areas are green and the rest of the leaf is a pale light green to yellow color. This is very stressful for the tree and it will not grow well. In this case the micronutrient manganese is not being taken up by the tree because the soil is not acidic enough for the chemical process to take place.
Before fertilizing, have your soil tested. Know what the needs of your trees are. Know what your soil supplies.
A soil test kit can be purchased from the MSU Bookstore.
More information on why to soil test.
More information on how to collect the sample.
More specific information on fertilizer types, determining the need and application is found in this link to the University of Minnesota Extension.