The most important part of tree fertilization is a soil or plant tissue test BEFORE any fertilizer is applied. Fertilizer is not “tree food” as some seem to believe. Trees use water, carbon dioxide, elements from fertilizer, and the sun’s energy to produce their own food. If essential elements are lacking or missing then fertilizer is necessary, because proper nutrient balances are important for tree growth. Too much of one nutrient is just as bad as not enough.
Many urban landscapes soils are disturbed, compacted, and lacking nutrients and trees showing signs of slow growth might be suffering from one or all of these problems. The only way to properly identify the problem is to have the soil tested. Trees need the following macronutrients: nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S), as well as many micronutrients. In most yards leaves are raked to encourage growth of turf. Removal of leaves prevents cycling of nutrients that occurs in more natural settings. Fertilization may be necessary to compensate for nutrients stripped from the root zone by leaf removal.
Spring and fall are the best times to add nutrients to the soil so they will be available for the main flush of growth which occurs in spring. Trees will continue to absorb nutrients after the first freeze in fall, before the soil freezes. Summer fertilization should be avoided. The salts in fertilizer can stress trees in times of low moisture. Mid to late summer fertilization could also stimulate new growth which is susceptible to freeze damage when the weather cools off.
Trees should not be fertilized with nitrogen when they are first planted or after root damage has occurred. Excess nitrogen at these times can cause new growth which roots cannot support.
The easiest way to fertilize your tree is to have Wellnitz Tree Care do it for you! We will ensure that the proper amount and correct type of fertilizer is applied over the entire root zone. Depending on the situation we can use slow release liquid fertilizer and inject it into the root zone or use a granular fertilizer sprinkled over the root zone.
310 Congress Street, Emporia, KS 66801 • 5709 SW 21st St., Suite 108, Topeka, KS 66604