When planting trees in the landscape, where should slow release fertilizer be placed?

Placing slow release fertilizer 2 to 6 inches below grade when planting trees is the most effective practice for several reasons. This depth allows the nutrients to be released in proximity to the tree's root zone, where they can be readily absorbed by the roots as they grow and expand. Fertilizing at this depth also helps protect the nutrients from being washed away by rain or irrigation, which can happen if fertilizer is applied at the soil surface.

By positioning the fertilizer below the surface, it reduces the risk of causing harm to the plant through direct contact with concentrated fertilizer granules, which can lead to root burn or other adverse effects. Additionally, soil microorganisms can help break down the slow release fertilizer, making nutrients available at a steady rate over time, which is ideal for the establishment of young trees.

The placement on the soil surface or above ground level would expose the fertilizer to the elements, increasing the likelihood of nutrient loss through evaporation or runoff. Applying it directly at the tree's base does not provide the same benefit of nutrient availability as when it is incorporated into the soil at the optimal depth.